Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons

G.B. Davis, N. Merrick and R. McLaughlan

Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review

technicalreport

2no.

CRC for Contamination Assessment and Remediation of the Environment

G.B. Davis1, N. Merrick2 and R. McLaughlan2

1CSIRO Land and Water

2University of Technology, Sydney

October 2006

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review

Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Technical Report series, no. 2

October 2006

Copyright © CRC CARE Pty Ltd, 2006

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This report should be cited as:

Davis, GB, Merrick, N & McLaughlan, R 2006, Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review,

CRC CARE Technical Report no. 2, CRC for Contamination Assessment and Remediation of the Environment, Adelaide, Australia.

Disclaimer:

This publication is provided for the purpose of disseminating information relating to scientific and technical matters. Participating organisations of CRC

CARE do not accept liability for any loss and/or damage, including financial loss, resulting from the reliance upon any information, advice or

recommendations contained in this publication. The contents of this publication should not necessarily be taken to represent the views of the

participating organisations.

Acknowledgement:

CRC CARE acknowledges the contribution made by Greg Davis of CSIRO Land and Water, and Noel Merrick and Robert McLaughlan of University

of Technology, Sydney, towards the writing and compilation of this technical report.

Front cover image: © istockphoto.com/JoeGough

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review i

Table of contents

Acknowledgements v

Executive summary vii

1. Introduction 11.1 Background 1

1.2 Project aims and fit with the overall site characterisation scope 1

1.3 The review team 1

2. Properties and typical behaviour of hydrocarbons 32.1 Properties of oils, fuels and hydrocarbon compounds 4

2.2 NAPL distributions 4

2.3 Dissolved phase plumes 5

2.4 Vapour phase 6

2.5 Fuel additives 6

2.5.1 Methyl-tertiary-butyl ether (MTBE) 6

2.5.2 Tertiary-butyl alcohol (TBA) 7

2.5.3 1,2 dichloroethane (EDC) and 1,2 dibromoethane (EDB) 7

2.5.4 Diisopropyl ether (DIPE) 7

2.5.5 Ethanol and methanol 7

3. Site characterisation strategies 113.1 Introduction and rationale 11

3.2 Traditional approach: phased investigations 11

3.2.1 Preliminary Phase 1 investigation 11

3.2.2 Initial or Phase 2 field investigation 12

3.2.3 Further site investigation 12

3.3 Accelerated site characterisation 12

3.3.1 Background 12

3.3.2 The Triad approach 13

3.3.3 Advantages and QC implications of Triad 13

3.3.4 Additional information and implications of Triad 14

4. Guidance and protocol documentation 154.1 Australian guidance and standards 15

4.1.1 National guidance – the NEPM 15

4.1.2 NSW Department of Environment and Conservation (NSW DEC) 16

4.1.3 Queensland Department of Environment (Qld DoE) 17

4.1.4 South Australian EPA 17

4.1.5 Victoria EPA 17

4.1.6 Western Australian Department of Environment and Conservation (WA DEC) 17

4.1.7 Australian Standards 18

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a reviewii

Table of contents

4.2 Overseas guidance, standards and information 18

4.2.1 US EPA 18

4.2.2 ASTM 19

4.2.3 United Kingdom 19

4.2.4 Europe and NICOLE 20

4.2.5 New Zealand Ministry for the Environment (NZ MfE) 21

4.3 Industry guidance and procedures 24

4.3.1 American Petroleum Institute (API) 24

4.3.2 Company A 25

4.3.3 Company B 25

4.3.4 Company C 26

4.3.5 Company D 26

5. Sampling and investigation technologies 275.1 Rapid site characterisation 27

5.1.1 Direct push techniques 27

5.1.2 Geophysics 27

5.1.3 Soil gas surveys 28

5.1.4 On-site and field analytical methods 28

5.2 New and not-so-new approaches 30

5.2.1 Depth-specific sampling 30

5.2.2 Purging boreholes 30

5.2.3 Sampling for organic compounds 31

5.2.4 NAPL characterisation 31

5.2.5 Flux estimation 32

5.2.6 Capillary fringe 32

5.2.7 Combined technologies 33

5.2.8 Directional and alternate drilling 33

5.2.9 Coupled reactive transport modelling 33

5.2.10 In situ or passive techniques 33

6. Synthesis and conclusions 356.1 Guidance documents 35

6.1.1 Purposeful 35

6.1.2 Adequate 35

6.1.3 Representative 36

6.2 Final observations 36

7. References 39

Appendices

Appendix A. Summary responses to the NEPM Issues Paper (used with permission) 47

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review iii

Table of contents

Tables

Table 1. Chemical and physical properties of some hydrocarbon compounds 8

Table 2. Industry, government and other site assessment protocols 22

Table 3. Table 1 from van Ree, D & Carlon, C 2003, ‘New technologies and future developments –

How much truth is there in site characterisation and monitoring?’, Land Contamination and

Reclamation 11(1), 37-48. Reproduced with permission 29

Figures

Figure 1. A petroleum leakage scenario leading to groundwater and vadose zone contamination, and

potential exposures 3

Figure 2. Depth profile of gasoline NAPL in soil from coring in a sandy profile, also showing possible

vapour and groundwater partitioning, and pathways of chemical mass flux 5

Figure 3. Depth profiles of gasoline vapour concentrations (TPH – soil gas) and major gases above an

NAPL-impacted zone 2.25–3.25 m below ground 6

Figure 4. Depth profile of BTEX and naphthalene concentrations and EC measurements in groundwater

near the source of a plume (right panel) and 40 m down hydraulic gradient (left panel) 31

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a reviewiv

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review v

Special thanks to BP Australia, Shell, ExxonMobil and Rio Tinto for providing their site investigation protocols, in

particular Andrew King, Eleanor Carswell, Perry Buckland and Stuart Rhodes. The NEPC Service Corporation (Bruce

Kennedy) is acknowledged for allowing publication of extracts from Review of the National Environment Protection

(Assessment of Site Contamination) Measure: Summary of Submissions received in relation to the Issues Paper for

the Review of the Assessment of Site Contamination NEPM. Discussions with Suresh Rao (Purdue University), Mike

Annable (University of Florida), Thomas Ptak (University of Tübingen), Christian End (URS), and colleagues at CSIRO

(Colin Johnston, Trevor Bastow) are appreciated. Thanks to the CSIRO Floreat Librarian Bernadette Waugh for

providing documents and books so rapidly and cheerfully. Also thanks to Dr Bradley Patterson (CSIRO) for carefully

reviewing the draft document.

Acknowledgements

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a reviewvi

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review vii

Characterisation and monitoring of petroleum-impacted

sites can be costly. Poor characterisation can lead to

uncertain mapping of the mass and distribution of

petroleum hydrocarbons in subsurface environments.

This in turn can lead to poor decisions which may

compromise human or environmental health or can

increase costs where remediation is prolonged, misapplied

or not well targeted due to lack of appropriate data.

From discussions between regulators, oil companies,

consultants, CSIRO, CRC CARE and other researchers

a scope of work related to site characterisation was

developed. CRC CARE agreed to a review stage project

proposal developed by CSIRO. The review stage is a first

step in a larger project to document techniques and

protocols that are used nationally and internationally,

to bring greater unity and improved approaches to

contaminated site assessment for petroleum impacts

in soil and groundwater environments of importance

to Australia.

This report:

1. documents typical properties of hydrocarbon

compounds and fuel/oil behaviours

2. provides an overview of traditional staged and

accelerated site characterisation strategies including

a discussion of the Triad approach

3. summarises available guidance, protocol and

standards documentation from state government

agencies and the NEPC, from industry, and from

overseas (United States, United Kingdom, Europe,

New Zealand)

4. documents some standard and not so standard

sampling and investigation techniques, and

5. provides summary comment.

Important issues, protocols and technologies related

to petroleum hydrocarbons in soil and groundwater

environments are highlighted.

The review provides an introduction to the multiphase

behaviour of petroleum hydrocarbons and the need to

address gas, liquid and solid phases (air, water and soil)

as well as the released non-aqueous phase liquid (NAPL)

in site assessments – and to address both the vadose

zone and groundwater. Fuels and oils are highly complex

mixtures that change their composition over time. The

intensity of investigative effort required in each phase is

somewhat dictated by environmental and jurisdictional

drivers, but also by typical properties of some petroleum

hydrocarbons, which govern the likely distribution of the

hydrocarbon product and individual compounds in the

subsurface. A limited discussion of fuel additives is

also given.

The importance of having site characterisation goals in

a risk-based framework is emphasised – what is the

overall goal and what is to be achieved at a site, what is

the compliance point, and what phase is dominant? To

assist with this, it is important to have a well developed

conceptual site model, along with a targeted program

of activity to improve the three-dimensional spatial and

temporal understanding of petroleum contamination

distributions in the subsurface. Such a program would

be developed out of a full conceptualisation of the site

model – inclusive of hydrogeology and soil strata, primary

fuel/compound types, the presence of additives,

compliance boundaries, principal transport mechanisms

in each phase, the proximity of receptors, etc. The intensity

of effort can be refined using data quality objectives,

where ‘data quality’ may more generally refer to data that

adequately represents the site conditions. It is concluded

that an investigation program needs to be purposeful,

adequate and representative to achieve its aims (i.e.

on PAR).

The traditional staged approach to site characterisation

(Phase 1 and Phase 2 environmental site assessments –

ESAs) is compared with accelerated site characterisation

(ASC) and in particular the so-called ‘Triad’ approach,

which links systematic planning and dynamic work

strategies with on-line and on-site measurement

techniques to enable site characterisation in a (hoped for)

single mobilisation. No implementation of ASC techniques

is apparent in Australia, despite savings estimates of up

to 40–50% for some applications in the United States

of America.

Information on some of the standard and more novel

site characterisation technologies is reviewed, including

direct push technologies, geophysics, on-site analytical

techniques, NAPL characterisation, capillary fringe and

vadose zones, combined technologies, directional and

alternate drilling, flux estimation techniques, passive and

on-line sampling/monitoring devices, and reactive

Executive summary

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a reviewviii

Executive summary

transport modelling. Further development, validation and

combination of technologies is required if rapid and cost-

effective site characterisation is to have greater adoption

in Australia.

Summary observations from the review include:

1. A risk-based approach should be taken as the starting

point for site characterisation, since this forces

consideration of the regulatory regime, exposure

pathways, and focuses effort on establishing a robust

conceptual model – with field investigations that

target the improvement and modification of this model.

2. A clear information objective is important –

embodying data quality objectives and achieving

representative sampling of a site.

3. Important to any site characterisation is the derivation

of a site conceptual model that integrates what is

already known about a site, and identifies both what

still needs to be discovered, and how that information

should be used.

4. Choices of site investigation approaches should

be made on the basis of improvement of the site

conceptual model. The site conceptual model

also serves as the basis for risk assessment and

remediation. The information needed for risk

assessment and remediation planning is not

necessarily the same.

5. Site characterisation plans need to be flexible and

adaptable to allow feedback on possibly real-time

results. This kind of dynamic approach to site

characterisation needs to be considered as a part

of overall site investigation strategy, before site

characterisation mobilisation. It also impinges on

the reliance on conventional sample-to-laboratory

systems, as laboratory data can take longer to be

generated. Dynamic approaches may also need

to encompass remediation planning.

6. If representivity is to be emphasised, perhaps the

analytical precision of conventional laboratory (off-

site) analyses could be traded off against greater

data intensity on-site, especially when comparing

sources of error from sampling, and sources of

uncertainty from site heterogeneity and variability.

7. For groundwater investigations, guidance

documents generally promote a minimum of three

or four boreholes. In practice, on average a greater

number of sampling boreholes is used. Greater use

could be made of statistical sampling theory, statistical

tests of significance, and geostatistical analysis to

handle aquifer and geochemical heterogeneity.

8. Site investigation data needs to be assessed over

time, as well as in space, so that trends in contaminant

behaviour can be assessed. The depth dimension is

often neglected in air, water and soil phases. Whilst

depth sampling of soils/sediments (whether in the

vadose zone or groundwater) is mentioned in several

guidance documents, it has not been formalised.

Depth-discrete sampling of groundwater is mostly

ignored.

9. A variety of site characterisation techniques are

available for on-site analyses, from on-site sensors to

geophysical techniques. Validation and improvement

is required to avoid false negative and positive

outcomes, and to build reliability and confidence into

rapid assessment practices.

10. Development of new tools for on-site use in site

characterisation is increasing – but if ASC or Triad

is to be pursued, further development of new or

novel sensor and site characterisation techniques

should be pursued, especially those that would

allow rapid on-site decision making and achieve

reliable outcomes at reduced cost. Combining

‘continuously available’ data with models on-line

could also be pursued. This is near readily available

for groundwater flow. However, where geochemistry

and reactive transport is important, on-line real-time

linkages between data collection and models is

problematic due to the computational intensity of

such codes.

11. The use of ‘direct push’ tools as opposed to

conventional drilling, and a variety of attachments

and sensors which can be used with these direct

push tools to collect site investigation information

is desirable. This allows more real-time information

gathering and implementation of dynamic site

characterisation strategies. Innovation in this area

should be encouraged.

12. In Australia, implementation of Triad would require

upskilling of all elements of site characterisation

(planning, on-site interpretation including sophisticated

modelling, and technology availability and deployment)

in consulting agencies and/or industry, and integration

of these skills with the regulatory approvals process –

possibly on-site.

13. Harmonisation of the regulation of site characterisation

through NEPM or other mechanisms may assist the

practice of site characterisation, but reduced flexibility

needs to be avoided to allow for continued innovation.

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review ix

14. Greater guidance on the use and application of

numerical models to integrate site characterisation

data could be useful. The Murray-Darling Basin

Commission issued guidelines for water resource

groundwater flow modelling in 2000. Prommer et al.

(2003) provided an initial basis for petroleum plumes

in groundwater. There are no Australian guidelines

for modelling multiphase hydrocarbon behaviour.

15. There is a need to continue to facilitate knowledge

transfer across regulators, contaminated site owners,

service providers and the academic community.

16. The scalability of site investigation plans and

technologies should be assessed – from UST and

service station scale, to depot and terminal scale

and perhaps refinery or multiple source complex

mega-site scale.

17. US documentation (ASTM, API, etc.) includes

management as part of guidance in many instances,

whilst the NEPM does not. Interestingly, the NSW

EPA Service Station Guidelines did include remediation

options as part of the guidance. A perceived difficulty

in embedding management options in such guidance

is the lack of stability in the range of technologies

on offer.

18. Research and innovation is needed to quantify and

optimise the value of gathering additional data so

as to minimise uncertainty during assessment – to

provide more precise definition of risks and costs

for clean-up applications. For example, whilst the

multiphase behaviour of petroleum hydrocarbons is

recognised, the value of extra data in any one phase

in reducing uncertainties in risk assessment or the

selection of remedial options is not well defined.

A number of challenges remain – none the least of these

is maintaining flexibility to adopt new ideas and technologies

and, where needed, change the regulatory and industry

norm to allow alternative assessments, whilst maintaining

protection of human health and the environment.

Executive summary

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a reviewx

1.1 BackgroundCharacterisation and monitoring of petroleum-impacted

sites can be costly. Poor characterisation can lead to

uncertain mapping of the mass and distribution of

petroleum hydrocarbons in subsurface environments.

This in turn can lead to conservative decision making

and increased costs where remediation is prolonged,

misapplied or not well targeted due to lack of appropriate

data. In addition, incorrect or incomplete data can lead

to poor decisions which may compromise human or

environmental health.

From discussions between oil companies, regulators,

CSIRO, other researchers and CRC CARE, a scope of

work and project proposal related to site characterisation

was developed. CRC CARE agreed to a project scope

developed by CSIRO in conjunction with UTS. This review

is the first step in a larger project to document techniques

and protocols that are used nationally and internationally,

and within industry, consultants and regulators – to bring

greater unity and improved approaches to contaminated

site assessment for petroleum spills in soil and groundwater

environments of importance to Australia.

1.2 Project aims and fit with theoverall site characterisationscope

This review has as its aim to produce a review of current

practices and protocols.

Several stages of the overall site characterisation project

were envisaged and presented to the Policy Advisory

Group in CRC CARE on 20 October 2005. These included:

1. Selection panel to appoint a Project Manager.

2. Appoint a single point of accountability (SPA) –

Project Manager.

3. Review international, national and industry

practice/guidance.

4. Establish a Project Advisory Group (PAG) (regulator,

industry, researcher, PL, SPA) – Gatekeepers.

5. Workshop issues (e.g. vertical delineation, spatial

and temporal density, new techniques, risk definition

versus targeted remediation, soil versus groundwater

sampling, pathways, land use).

6. Review existing data sets and link exposure

pathway/end-use scenarios to data capture intensity.

7. Review outputs of Steps 3–6, as input to Step 8.

8. Scope and build an expert system – risk pathways

versus remediation, conceptual model of site – to

give a recommended sampling plan.

9. Build a guidance document.

10. Make the expert system and guidance web-enabled

(value proposition).

This review targets the completion of Stage 3 of this

scope – that is the review of national and international

approaches, and regulatory and industry practices.

There is a large amount of literature (papers, guidance

documents, protocols) and experience regarding site

characterisation. This includes planning, guidance, QA/QC,

standards for sampling, risk-based decision making,

sampling statistics, sample collection and handling,

investigation techniques, and field and laboratory

analytical techniques and protocols. In this review it is not

possible to review or synthesise all the information. Here

we will limit discussion to immediate concerns around

the guidance documentation, types of techniques used

to collect samples from soil, water and gas phases, the

advantages and disadvantages of some techniques, and

some aspects of non-standard techniques available to

investigate sites.

Details of additional research that may be required to be

carried out are not given here – these will come from the

workshop indicated as Step 5 in the list above.

1.3 The review team The review stage of the project has been led by CSIRO

(collation, interpretation, reporting) with UTS providing

the review of this document. Other subsequent stages of

the project as outlined in Section 1.2 may be led by others.

1. Introduction

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review 1

CRC CARE Technical Report no. 2 Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons – a review2


Common sources of hydrocarbons are crude oil, petroleum

fuels such as gasoline, diesel, kerosene and aviation fuel,

other specific blends, and single-component hydrocarbon

liquids that are used as solvents (such as benzene).

Hydrocarbons are also used in the manufacture of many

other products.

Petroleum fuels and crude oil are mixtures of hundreds of

hydrocarbon compounds, and greater or lesser amounts

of other compounds, and in some cases specific additives

such as methyl-tertiary-butyl ether (MTBE). Components

of fuels and oil partition to air, water, soil and biological

phases, and can exist as separate phase liquids (or non-

aqueous phase liquids – NAPLs). As such they can be

distributed in multiple phases in the subsurface – each

of which has its own primary transport and attenuation

processes (e.g. advection, diffusion, dispersion, sorption,

biodegradation), and ultimately these govern the

distribution and potential risks posed by hydrocarbons

in the subsurface. To add complexity, petroleum

compounds biodegrade and transform to alter the

composition of NAPL, plumes and vapour phases,

creating new compounds and different risk profiles

over time.

Such complexity requires careful attention to the objectives

and goals of any investigation and site characterisation

campaign. In this section we provide detail on petroleum

hydrocarbon properties, and some description of their

behaviour and characteristics in each phase. These are

important to be able to design investigations that will

yield meaningful outcomes, and to assess the level of

effort required in each potentially impacted phase. In

particular, we give some general description of petroleum

behaviours in the context of a spill of organic liquid and

how that liquid may potentially present risks via a variety

of phases and exposure pathways – depicted simply

in Figure 1.

2. Properties and typical behaviour of hydrocarbons

Figure 1. A petroleum leakage scenario leading to groundwater and vadose zonecontamination, and potential exposures. The ‘accumulated product’ and ‘residualcontamination’ in the schematic are non-aqueous phase liquids (or NAPLs), whichcan contain soluble and volatile contaminants that can partition into gas, aqueous,aquifer sediment and biological or other organic phases in the subsurface.


Also, there are a range of chemicals and compounds

that have been added to fuels, or remain at residual

levels in the source oils. These include:

• methyl-t-butyl ether (MTBE)

• tertiary butyl alcohol (TBA)

• 1,2 dichloroethane (EDC)

• 1,2 dibromoethane (EDB)

• diisopropyl ether (DIPE)

• ethanol

• methanol

• lead

• vanadium.

Significant detail is not provided on these compounds,

although some discussion is contained in Section 2.5.

In addition, while the primary chemicals are of concern

at a release site, other analytes may be important. For

example, for a natural attenuation assessment the oxic

status of the soil/aquifer, or the abundance of other

electron acceptors such as sulfate may be important to

assess, to enable a more complete conceptual model of

hydrocarbon fate and likely behaviour to be developed.

2.1 Properties of oils, fuels andhydrocarbon compounds

Typically oils and refined products would be categorised

as (API 1996):

• crude oils

• gasolines

• middle distillates – such as diesel, kerosene, jet fuels

and lighter fuel oils

• heavier fuel oils and lubricating oils

• asphalts and tars

• coke.

Gasoline is primarily made up of a range of aliphatic

compounds (e.g. ethane, propane, hexane) and aromatic

compounds (e.g. benzene, toluene, ethylbenzene,

xylenes). Middle distillate fuels are made up of a range

of compounds, similar to gasoline, but with a range of

compounds that are more dense, less volatile, less mobile

and less water soluble. They contain low concentrations

of aromatic compounds. Heavier fuel oils have a larger

mole fraction of higher carbon number compounds and

as such, these fuels have greater viscosities and low

mobility in the subsurface.

The principal fluid properties controlling mobility are

viscosity and density. Of course, the properties of the

aquifer sediments and soils, and water and air in contact

with the oils or fuels play a role in the overall mobility of

the oils and oil products. Crude oil may have viscosities

ranging from 5–180 centipoise but more typically 10–100

centipoise, at 15°C. Gasoline has a viscosity of less than

one centipoise, diesel has a value of 2–3 centipoise, while

water has a viscosity of 1.14 centipoise at this temperature.

Densities are 0.998 g/mL for water, 0.832–0.914 g/mL

for crude oils, approximately 0.73 g/mL for gasoline and

0.83–0.84 g/mL for middle distillates. As such, oils and

refined products are less mobile than water, being more

viscous and less dense.

Table 1 is a compilation of some properties of a range

of individual hydrocarbon compounds, additives and

weathering products found in fuels and oils. Many of

the compounds are highly volatile and most are

sparingly soluble.

2.2 NAPL distributionsFree hydrocarbons, free product, liquid hydrocarbon,

phase-separated hydrocarbons (PSH) and free phase

hydrocarbons are all terms used to denote light non-

aqueous phase liquid (or LNAPL). LNAPL hydrocarbons

are less dense than water (hence light), and can infiltrate

through the unsaturated zone and often accumulate

across the zone of fluctuation of the water table

(CONCAWE 1979). Under groundwater gradients and

NAPL heads, NAPL will then move across the top of the

saturated zone. Seasonal and other oscillations of the

water table produce vertical movement of LNAPL, which

can smear the LNAPL across the zone of oscillation

(Steffy et al. 1995). Thus LNAPL at residual (non-mobile)

soil concentrations can occur both above and below the

water table. Residual concentrations vary depending on

the nature of the porous media. In some sands and finer

materials, this can amount to saturations of 0.01–0.3

(Johnston & Adamski 2005; Johnston & Patterson 1994).

NAPLs are mobile depending on aquifer properties

(hydraulic permeability) and NAPL properties (e.g.

viscosity, interfacial tension), but are much less mobile

than dissolved or gaseous phase hydrocarbons.

The extent of vertical movement of an NAPL, and a spills

potential to reach groundwater, will depend on the

amount and type of NAPL available for percolation, and

the nature of the porous medium (e.g. air and water-filled

porosity). Where pore spaces are interconnected (e.g.

sands), CONCAWE (1979) and others (Johnston 1997)




provide some measures of the depth to which a given

volume of oil can penetrate the ground.

NAPL properties and its composition change over time,

due to partitioning of hydrocarbon components to the

various water, air and soil phases, and weathering

processes. Initially fresh diesel may be relatively mobile,

with the majority of soluble material being aromatic

compounds, but upon weathering the majority of the

soluble material may be a vast number of polar compounds

which are highly soluble, but only representing a small

fraction of the mass of the remaining NAPL phase.

The distribution of a spilt NAPL in a sandy aquifer may

vary from a few centimetres thick to several metres,

depending on the zone of water table fluctuation and

other layering features within the aquifer strata. Figure 2

shows a typical depth profile for gasoline in the sand

aquifer in Perth (see Davis et al. 2005). In this case, the

NAPL gasoline is distributed over a vertical depth interval

of up to 2 m with the majority of the mass over a depth

interval of 1 m. The peak concentration is nearly 90,000

mg/kg residing in the vicinity of the capillary fringe. Note

that a second peak appears below the water table.

Johnston and Patterson (1994) describe diesel NAPL

distributions in a similar sandy profile.

In fractured aquifers or heavier soils the distribution of

petroleum NAPL may be quite different. In tight clays,

coarse conduits may provide pathways for NAPL

movement (Johnston & Adamski 2005), and in fractures

the distributions may be even more complex depending

on interconnectivity of fractures etc.

2.3 Dissolved phase plumesContact of LNAPL and groundwater gives rise to

leaching of soluble constituents from the NAPL which

move with groundwater to create groundwater plumes.

Of the components leaching from petroleum fuel NAPLs,

branched or straight chain alkanes are sparingly soluble,

and solubilities decrease with increasing carbon number

and molecular weight. Mono-aromatic compounds and

polynuclear aromatic hydrocarbons (PAHs) are more

soluble and prevalent in gasoline (cf. diesel) fuels, and are

considered to produce adverse effects on groundwater

quality (Davis et al. 1993). In addition, as mentioned

above, LNAPL composition changes with time and so

do the soluble fractions leaching into groundwater. In

particular, it has been noted for weathered diesel that

high concentrations of polar compound can occur in

groundwater in contact with the diesel. In some cases

this can give an equivalent dissolved total petroleum

hydrocarbon (TPH) concentration in groundwater that

is higher for an older diesel source (50 years old)

compared to fresh diesel.

Of the mono-aromatics (benzene, toluene, ethylbenzene,

xylene isomers or BTEXs) benzene is a known carcinogen

and can be persistent under some anoxic conditions

which prevail around oil spillages (e.g. see the investigation

of Thierrin et al. 1993). Microbial activity in groundwater

environments gives rise to biodegradation of the petroleum

hydrocarbons, given that electron acceptors are available

to the microbial communities – electron acceptors

include oxygen, nitrate, iron oxides, manganese oxides,

sulfate or carbon dioxide. Benzene has been reported to

be degraded under anoxic conditions (Edwards & Grbic-

Galic 1992; Wilson et al. 1989), although this does not

seem to be ubiquitous (Davis et al. 1999), unlike

degradation of toluene and the xylene isomers (Thierrin

et al. 1993). Johnson et al. (2003) provide a review of the

anaerobic biodegradation of benzene. All the BTEX

compounds are readily degraded under aerobic conditions.

A summary of trends of typical natural biodegradation

Figure 2. Depth profile of gasoline NAPL in soil fromcoring in a sandy profile, also showing possiblevapour and groundwater partitioning, and pathwaysof chemical mass flux.

of fuels is found in Wiedemeier et al. (1999), and a more

recent review is being prepared under the Natural

Attenuation Petroleum Issues Scope of CRC CARE.

2.4 Vapour phasePartitioning of organic chemicals into the air phase can

occur either from the NAPL, from adsorbed sources in

the soil profile, or from groundwater in the subsurface.

Hydrocarbon vapours have the potential to migrate from

the subsurface source zones through the soil profile to

the ground surface. The rate and extent of movement

depends on a range of factors – including chemical and

soil properties. Movement of the organic vapours is

primarily governed by diffusion in the soil gas, although

local wind (and other) conditions can also induce advective

movement in the shallow subsurface. Whether the vapours

discharge to the atmosphere will depend on ground

surface conditions, the relative magnitudes of transport

processes and biodegradation, and in particular, the

presence of built structures at the ground surface.

For a gasoline spill in a shallow sand profile Davis et al.

(2005) report hydrocarbon vapour depth profiles and

biodegradation processes. Davis et al. (2004) published

a review of the assessment, behaviour and exposures

posed by vapours in the subsurface. They include some

discussion of investigative techniques. A summary of

typical vapour behaviours was published in Davis et al.

(2006).

A typical vertical profile is shown in Figure 3. This shows

the movement of vapour TPH from a gasoline NAPL

zone at a depth of 2.25–3.25 m with decreasing

concentrations to a depth of 1.25 m below the ground

surface. Oxygen concentrations decrease from the

atmosphere to the same depth, largely due to aerobic

biodegradation at the interface where TPH vapour and

oxygen concentrations decrease to zero.

2.5 Fuel additives

2.5.1 Methyl-tertiary-butyl ether (MTBE)

MTBE is a fuel oxygenate – it was used extensively in the

US as a lead replacement in gasoline, to ensure cleaner

burning of fuel to minimise air pollution. In Australia, MTBE

was not added in significant quantities to fuels. Imported

fuels may have had higher concentrations of MTBE, but

from 2004 in Australia MTBE was restricted to levels of

1% or less by volume (DEH 2004). This restriction was

in recognition of the possible impacts of MTBE on

groundwater quality.



Figure 3. Depth profiles of gasoline vapourconcentrations (TPH – soil gas) and major gases abovean NAPL-impacted zone 2.25–3.25 m below ground.The vertical axis is depth below ground surface.



MTBE can be a significant potential groundwater

contaminant due to its mobility, recalcitrant nature and

potential toxicity. MTBE is highly soluble – 40,000–50,000

mg/L for single phase solubility. Where MTBE makes up

10% of a gasoline, this can lead to concentrations in a

water phase (e.g. groundwater) of 5000 mg/L. In contrast,

where MTBE is not present the typical total concentration

of soluble gasoline components might be 100–150 mg/L.

MTBE sorbs only weakly to aquifer materials, therefore,

sorption will not significantly retard MTBE's transport

relative to groundwater movement. In addition, MTBE

can be resistant to degradation in groundwater although

studies have shown that biodegradation can occur under

a range of conditions, albeit perhaps more slowly than

some BTEX biodegradation (see US EPA 2001).

2.5.2 Tertiary-butyl alcohol (TBA)

TBA is a fuel oxygenate – used as an octane booster

in gasoline – but is also an impurity in MTBE and a

degradation product of MTBE. TBA can be a significant

potential groundwater contaminant due to its mobility,

recalcitrant nature and potential toxicity.

2.5.3 1,2 dichloroethane (EDC) and 1,2 dibromoethane (EDB)

EDB and EDC were both added to gasoline fuels as lead

scavengers – the extent of use in Australia is uncertain.

Since leaded gasoline is now banned, EDC and EDB are

no longer used for this purpose, and as a result were

phased out some time ago.

2.5.4 Diisopropyl ether (DIPE)

DIPE is another of the possible ether oxygenates that

can or have been added to fuels to provide cleaner air

emissions. In some cases DIPE was substituted or part-

substituted for MTBE in fuels. No data was found to

indicate its use in Australian fuels – although the fuels

standard imposes a 1% by volume upper limit.

2.5.5 Ethanol and methanol

Ethanol and methanol and other bio-fuels are being

increasingly viewed favourably as blends or alternatives

to traditional petroleum fuels. Ethanol was restricted to a

maximum of 10% in Australian fuels in 2004 (DEH 2004).

Niven (2005) provides a critical review of the use of ethanol

in fuels and there has been increasing research and

interest in the environmental consequences of such shifts

to bio-fuel use. Niven (2005) points out that increased

ethanol use in fuel blends can increase the solubility of

other fuel constituents (such as the BTEX) by 30–210%

(Corseuil et al. 2004), and the presence of ethanol in a

fuel spilled into groundwater may inhibit the biodegradation

of the petroleum hydrocarbons (see e.g. LLNL 2001, and

references in Niven 2005). This may result in the extension

of plumes of the BTEX compounds in groundwater.



Table 1. C

hemical and

physical p

ropertie

s of some hydrocarbon co

mpoun

ds

Compoun

dCAS

Molecu

lar

Den

sity

Aque

ous Hen

ry’s Law

Hen

ry’s Law

Octan

ol-water

Vapour

Vapour

number

weight

(g cm

-3)

solubility co

nstant, H

cco

nstant at

partitioning

pressure

den

sity

(g m

ol-1)

(mg L

-1)

(kPa m

3mol-1)

25 0C, K

gw

coefficient (K

ow)

(kPa)

relative to

(dimen

sionless)

(dimen

sionless)

air (air =1)

eth

ane

74-8

4-0

30.0

70

.54

46

i5

7.0

i5

0.6

i2

0.4

--

1.0

5 e

eth

ene

74-8

5-1

28.0

50

.56

78

i1

34

.0 i

21

.1 i

8.5

2-

-0.9

7 e

pro

pane

74-9

8-6

44.1

00

.49

3 i

67

.1 i

71

.6 i

28

.9-

-1.5

5 e

pro

pene

115-0

7-1

42.0

80

.50

5 i

20

1 i

21

.3 i

8.6

0-

-1.4

8 e

penta

ne

109-6

6-0

72.1

50

.62

64

0.0

f1

28

c5

6.3

2450

d68.4

f2.5

e

hexane

110-5

4-3

86.1

80

.65

51

2.4

f1

31

c5

7.6

7940 d

20.2

f3.0

e

cyc

lohexane

110-8

2-7

84.1

60

.77

95

7.5

f1

9.5

c8

.58

2750 d

12.7

f2.9

e

benze

ne

71-4

3-2

78

.12

0.8

78

71

79

0 a

0.5

64

c0

.22

5138 a

11.7

g2.7

7 e

tolu

ene

108-8

8-3

92

.15

0.8

66

94

69

a0

.64

4 c

0.2

57

436 a

3.7

5 g

3.1

4 e

eth

ylb

enze

ne

100-4

1-4

10

6.1

70

.86

71

40

a0

.81

5 c

0.3

25

1480 a

1.3

0 g

-

m-x

ylene

108-3

8-3

10

6.1

70

.86

42

19

7 b

0.6

75

c0

.26

91100 b

1.1

3 g

3.6

6 e

p-x

ylene

106-4

2-3

10

6.1

70

.86

11

19

8 h

0.6

14

c0

.27

01410

1.1

9 g

3.6

6 e

o-x

ylene

95-4

7-6

106

.17

0.8

80

21

76

b0

.42

4 c

0.1

69

1100 b

0.9

12 g

3.6

6 e

1,3

,5-t

rim

eth

ylb

enze

ne

108-6

7-8

120

.20

.86

52

97

.5 b

0.8

03

c0

.32

02880 b

0.3

45 g

4.1

5 e

sty

rene

100-4

2-5

104

.15

0.9

06

0 i

25

1 i

0.3

i0

.12

11120 i

3.6

e

nap

hth

ale

ne

91-2

0-3

12

8.1

91

.02

53

29

.4 a

0.1

25

c0

.04

96

2090 a

0.0

11 g

4.4

2 e

phenanth

rene

85-0

1-8

178

.22

91

.06

31

.10

.00

32

4

1-m

eth

ylnap

hth

ale

ne

90-1

2-0

14

2.2

01

.02

02

28

.4 a

0.0

36

5 c

0.0

14

56610 a

0.0

08 g

-

2-m

eth

ylnap

hth

ale

ne

91-5

7-6

14

2.1

97

1.0

05

82

50

.05

1

1,5

-dim

eth

ylnap

hth

ale

ne

571-6

1-9

15

6.2

23

3.1

0.0

36

1-e

thyl

nap

hth

ale

ne

1127-7

6-0

15

6.2

23

1.0

08

10

.10

.03

9

n-C

18

593-4

5-3

254

.49

50

.77

70

.00

6

1-o

cta

decanol

112-9

2-5

270

.49

40

.81

20

.11

1-d

ecanol

112-3

0-1

15

8.2

80

.82

93

7



Table 1. (co

nt.)Che

mical and

physical p

ropertie

s of some hydrocarbon co

mpoun

ds

Compoun

dCAS

Molecu

lar

Den

sity

Aque

ous Hen

ry’s Law

Hen

ry’s Law

Octan

ol-water

Vapour

Vapour

number

weight

(g cm

-3)

solubility co

nstant, H

cco

nstant at

partitioning

pressure

den

sity

(g m

ol-1)

(mg L

-1)

(kPa m

3mol-1)

25 0C, K

gw

coefficient (K

ow)

(kPa)

relative to

(dimen

sionless)

(dimen

sionless)

air (air =1)

2-m

eth

ylcyc

lohexanone

583-6

0-8

112

.16

90

.94

22

50

0

meth

anol

67-5

6-1

32.0

42

0.7

91

mis

cib

le-

0.0

00

11

--

-

eth

anol

64-1

7-5

46.0

69

0.7

89

mis

cib

le-

0.0

00

21

--

--

0.0

00

26

meth

yl t

ert

iary

-buty

l eth

er

1634-0

404

88

.14

90

.74

14

3,0

00

--

0.0

23

-0.1

2-

--

(MTB

E)

54

,00

0

tert

iary

-buty

l alc

ohol (

TB

A)

75-6

5-0

74.1

22

0.7

86

mis

cib

le-

0.0

00

48

--

--

0.0

00

59

diis

op

rop

yl e

ther

(DIP

E)

108-2

0-3

10

2.1

80

.72

42

,00

0-

-0

.19

5-0

.41

--

-

9,0

00

1,2

dic

hlo

roeth

ane (E

DC

)107-0

6-2

98

.96

1.2

35

1i

75

79

i0

.14

i0

.04

-0.0

57

30.2

i10.5

i3.4

e

1,2

dib

rom

oeth

ane (E

DB

)106-9

3-4

187

.86

2.2

-2.7

34

,00

00

.01

33

1.5

6.5

aM

ulle

r and

Kle

in 1

992

bS

uzu

ki 1

991

cYaw

s e

t al.

1991

dS

RC

Phys

Pro

p D

ata

base 2

004

eC

hem

Fin

der

2004

fM

acka

y and

Shiu

1981

gM

acka

y et

al.

1992

hH

ine a

nd

Mooke

rjee 1

975

iLid

e 2

000

3.1 Introduction and rationaleThere are a number of activities that can trigger the need

for site characterisation and/or sampling. These can

include:

• site re-development

• regulatory or industry review

• community complaint or concern

• remediation design or validation.

The extent of investigation and site characterisation will

depend on the objective of the required action. It may be

a need for a once-off investigation or sampling of existing

wells, the quantification of risk at a site, a specified tier

assessment, determination of contaminant distributions

as input to remedial option selection, or the establishment

of long-term monitoring at a site, perhaps for monitored

natural attenuation or for other purposes. In addition, the

level of effort will depend on the environmental phases

(air, water, soil, biota, NAPL) that may require investigation,

and the variety of techniques required and available to

achieve the objectives of the investigation. Overall, the

aim of a site characterisation should be to provide a high

quality conceptual site model (CSM) that can support

decisions about exposure to contaminants, possible site

clean-up and re-use, and long-term monitoring, taking

account of the partitioning and other hydrocarbon

behaviours discussed in Section 2.

Here the focus is on ‘adequate’ site characterisation – to

achieve reduced uncertainty on hydrocarbon mass and

distribution in the subsurface, to allow decisions about

potential exposure and remedial design. It is recognised

that a site investigation would typically be carried out in

stages or phases, although increasingly accelerated

minimal stage investigations are being promoted (see

Section 3.3).

3.2 Traditional approach: phasedinvestigations

Traditionally, several stages or phases of investigation are

performed at contaminated sites. It is common for a site

characterisation effort to include:

• a preliminary or Phase I environmental site

assessment (ESA) investigation – perhaps a site visit

and a desk-top study including the collation of existing

data and information

• a field campaign or Phase II ESA – to collect additional

site data at a level of intensity to satisfy initial regulatory

and site assessment questions (possibly following a

tiered assessment)

• a more intensive field campaign that would better

quantify masses and distributions of chemicals in

several phases – to satisfy next level tier assessments

or for remedial design.

Often such steps in an investigation will be interspersed

with data interpretation, modelling, regulatory submission

and discussion and agreement for subsequent stages

of investigation. As such the process of site assessment

is often cyclic, with multiple excursions to the field and

periods of data synthesis, interpretation and reporting.

Over the last decade, the level of characterisation or

assessment is increasingly risk-based and a tiered

approach to site assessment is often carried out. This

was somewhat formalised in the United States via ASTM

(1995), which was specifically designed for petroleum-

impacted sites.

In addition, rapid site assessment techniques have also

been increasingly investigated to achieve cost savings

and allow for single or minimal field excursions. This is

discussed in a subsequent section.

3.2.1 Preliminary Phase I investigation

For a preliminary Phase I investigation, commonly, the

aim is to develop a conceptual model of the site and

an understanding of the likely drivers of risk and action.

This entails an understanding of the site conditions,

including:

• locale (regional and local setting), vicinity of dwellings,

water bodies, groundwater bores

• soil type, stratigraphy, geology, hydrogeology, bore

locations and use

• history of the site – land use, fuel and other chemical

storage, spill history

• chemical properties

• site infrastructure (above and below ground), design

drawings


3. Site characterisation strategies

• visual state of the site – soil and vegetation

• likely or potential receptors.

The outcome of a preliminary investigation would be a

report summarising the key data and information, and

development of the conceptual site model, including

schematics of distributions and possible hydrocarbon

transport, and a recommended investigation plan.

Although preliminary, it is a critical phase and should be

carried out thoroughly to ensure plans and objectives for

the subsequent phase of investigation are fully developed.

Various guidance documents provide greater detail on

this (see Section 4), and one or two texts are available

(see e.g. Hess 1998).

3.2.2 Initial or Phase 2 fieldinvestigation

This may be the only phase or stage of active field-based

investigation of a site, or the precursor to additional

stages of investigation depending on the complexity of the

site and the regulatory and remedial demands of a site.

Often the scope of this phase will attempt to:

• fill data gaps identified in the preliminary investigation

• validate and improve the site conceptual model

• provide adequate data to satisfy regulatory requirements

• provide adequate data to determine likely exposures

and to carry out a risk assessment

• provide data that would allow input to mitigation

strategies, if feasible or warranted at this stage.

At a minimum, this would typically require sampling of

soils on-site and/or sampling groundwater from existing

wells if present. However, this phase is likely to involve

a broader range of additional field activities, possibly

including drilling, geoprobing, coring, soil sampling, test

pits, NAPL sampling, soil gas sampling, geophysical

techniques, spear probing, and possibly other new

investigation techniques depending on the complexity

of the site, the questions needing to be answered, and

whether they are deemed to add value.

The output from this phase is an improved conceptual

site model and maybe a predictive model, possibly a risk

assessment, and an assessment of site conditions

relative to threshold values and regulatory drivers.

3.2.3 Further site investigation

It is not uncommon to have cyclic field mobilisations.

Data from earlier field excursions, modelling and discussion

with regulators, preliminary costings on remedial options,

etc. may require additional characterisation work.

Subsequent phases of investigation may be required to:

• further refine the site conceptual model

• validate or refine a numerical model of the site

• validate or assist with design of remediation if required

• provide additional data for risk assessment.

These may be required where data gaps and uncertainties

still exist, where the areal extent of impact is much

greater than initially assumed, the site is overly complex

and where regulatory requirements need to be met.

3.3 Accelerated sitecharacterisation

3.3.1 Background

In the early 1990s, it was recognised that many site

investigations that progressed in multiple stages were

often prolonged and costly, and perhaps not yielding

optimal results. Various agencies, mostly in the United

States (e.g. U.S. Department of Energy (DOE)), saw the

need to expedite site investigations (Burton 1993). A focus

of the multistage approach was carefully documented

analytical procedures which became standards, and

that were legally defensible. The multistage approach

spawned valuable high-end analytical procedures and

documentation, as well as high quality data in many

cases. However, it was increasingly recognised that the

approach also led to delays and added expense in

resolving contaminated site issues.

A number of government, academic and private sector

institutions contributed to further strategic and practical

considerations related to accelerated site characterisation

(ASC) (e.g. Robbat 1997). European academic and

government institutions pursued similar initiatives

(referred to as ‘Network Oriented Risk Investigation

for Site Characterization’, or ‘NORISC’). NORISC

emphasised early and active stakeholder involvement in

the establishment of clean-up goals and placed strong

emphasis upon the use of on-site analysis software. The

US EPA coordinated efforts in the US with other Federal

and State agencies to further develop and organise

resources that would support the ASC approach. ASTM



(1998) and others (US EPA 1997) developed standardised

guidance on utilising accelerated (single mobilisation)

approaches for petroleum release sites. Primarily these

revolved around technologies that could be utilised to

carry out ASC, including:

• geophysical techniques

• soil gas surveys

• direct push technologies

• field methods for analysis of petroleum hydrocarbons.

These will be discussed later in the report.

In the USA the ASC approach was further refined and

formalised to include more of the strategic and dynamic

planning required to achieve a single mobilisation site

characterisation. One form of it has been termed the

Triad approach. Recently, the Triad Resource Center

was set up to resource and promote the approach (see

http://www.triadcentral.org/index.cfm).

3.3.2 The Triad approach

Simply, the Triad approach has as its goal to manage

(reduce) decision making uncertainty using improved

planning and technology, resulting in accelerated

schedules, reduced project costs, and ultimately improved

remedial outcomes. As indicated earlier, for any site

characterisation strategy the overall aim is to provide

a high quality conceptual site model (CSM) that can

support decisions about exposure to contaminants, site

clean-up and re-use, and long-term monitoring – but

Triad seeks to deliver this with minimal mobilisations.

The Triad approach has three key components:

1. systematic planning

2. dynamic work strategies, and

3. on-site techniques and real-time data gathering and

interpretation capabilities.

Systematic planning seeks to ensure that the level of

detail in project planning matches the intended use of the

data being collected. Systematic planning is undertaken

so that the project uses resources effectively, and is

technically sound and defensible to reach defined clean-

up goals. A team of multidisciplinary, experienced technical

staff is required to translate project goals into realistic

technical objectives. The CSM is the planning tool that

integrates the information that is already known about

the site, and helps identify additional information that

must be obtained. The systematic planning process ties

project goals to individual activities necessary to reach

these goals by identifying data gaps in the CSM. The

CSM is then used to direct the gathering of needed

information, to develop and improve the CSM as work

progresses and data is gathered.

A dynamic work strategy requires flexibility, on-ground

expertise in a number of technical areas and relies on

real-time data to reach decision points. Prior to a field

excursion the logic for decision making needs to be

identified and responsibilities, authority and lines of

communication need to be clearly established. Dynamic

work strategy implementation relies on timely project

decisions needed to reach investigation goals. It uses

a decision-tree and real-time uncertainty management

practices to reach critical decision points in as few

mobilisations as possible. Success of a dynamic approach

depends on the presence of experienced staff in the field

who can make decisions based on the decision logic and

their capability to deal with new data and unexpected

issues as they arise. Field staff need to maintain close

communication with regulators or others overseeing the

project during implementation of dynamic work plans.

On-site analytical tools, rapid sampling platforms, and

on-site interpretation and management of data make

dynamic work strategies possible. Real-time measurement

tools are among the key streamlined site investigation

tools because they provide the data that are used for on-

site decision making. The tools are a broad category of

analytical methods and equipment that can be applied at

the site. They include methods that can be used outdoors

with hand-held, portable equipment, as well as more

rigorous methods that require the controlled environments

of a mobile laboratory (transportable). During the planning

process the type, rigour, and quantity of data needed

to answer the questions raised by the CSM need to be

identified. Those decisions then guide the design of the

sampling and the selection of analytical techniques.

Linking these in real time during a single site investigation

is the key to success with the Triad approach.

3.3.3 Advantages and QC implicationsof Triad

The Triad approach controls decision uncertainty by

targeting the principal components of data uncertainty –

including the sampling, analytical and relational

uncertainties produced by data collection efforts – but

attempts to do so cost-effectively. The claimed key

benefits for managers include reduced project costs,

expedited schedules, enhanced stakeholder concurrence,





and improved site decision making. It is claimed that cost

savings of up to 50% can be achieved using Triad, and

that the savings increase with the complexity of the site.

This is attributed to a clearer articulation of the goals and

decision logic so that the dynamic work strategy can

reduce the number of site visits – thus reducing targeted

uncertainties at reduced cost.

It should be emphasised that the Triad approach cannot

compromise on quality data collection or interpretation

as the data needs to satisfy regulatory requirements, and

support decisions on remediation and exposures. In that

sense the goals of Triad quality control (QC) components

are the same as those of more traditional programs, to

generate data of known quality whose quality

characteristics are documented, verifiable, and technically

defensible, and to identify in a timely manner issues or

problems that will adversely affect performance and that

require attention. In addition, Triad-based programs may

require QC in the field that is perhaps more rigorous and

indeed flexible. The intensity and frequency of QC

activities may change over time. It is likely that at the start

of the mobilisation high intensity QC data (e.g. duplicates,

calibration checks) are collected allowing less QC once

uncertainties and performance measures are better

understood. Or indeed, when field data show changed

conditions (e.g. increased soil moisture) or multiple zeros,

additional or changed QC sampling and procedures may

be required.

3.3.4 Additional information andimplications of Triad

References and documentation relating to the Triad

approach can be found at:

• The Triad Resource Center –

http://www.triadcentral.org/index.cfm

• ITRC 2003, Technical/Regulatory Guidelines: Technical

and Regulatory Guidance for the Triad Approach: A

New Paradigm for Environmental Project Management.

The Interstate Technology & Regulatory Council (ITRC)

Sampling, Characterization and Monitoring (SCM) Team

has prepared a guidance document for the Triad approach.

It introduces the Triad approach as an integrated

package of concepts leading to improved practices for

how contaminated site work can be conducted.

Implementation of the Triad approach requires:

• clear regulatory or agency goals

• detailed conceptual site model (so an initial desk-top

study would be required)

• extensive and thorough planning prior to mobilisation

• transparency amongst operators, agencies and staff

involved in the mobilisation.

Such an approach would challenge the norm in

Australia, demand excellence in planning, interpretation

and technique deployment, and would demand close

interaction between regulatory, industry, consultant,

contractor and associated staff to achieve the

best outcomes.

Of course a number of the components of Triad could

be (and perhaps should be) utilised in any site

characterisation or mobilisation campaign to improve

multistage investigations. Improved strategic and

dynamic planning, along with better, validated and on-

site or real-time techniques, would always add value.


Many site assessment guidance documents exist at

state, national and international levels, and within industry,

and many journal and conference papers are available.

All the literature is not reviewed here. A number of

documents are listed in the references.

Some industry and government organisations were

approached to supply their standard site investigation

procedures, including BP, Shell, Caltex, ExxonMobil, Rio

Tinto and the Department of Defence. Protocols provided

and others available through the NEPC or otherwise are

listed in Table 2.

There is a range of international and Australian

documentation that could be considered. The guidance

and protocols most recognised and acknowledged

internationally are those produced by the United States

Environment Protection Agency. Australia’s national

guidance is embodied in the National Environmental

Protection (Assessment of Site Contamination) Measure

promulgated in 1999 (NEPC 1999a), and there are some

standards available. A number of the states of Australia

also have guidance documentation – some of these

are more or less specific to petroleum hydrocarbon-

impacted sites.

Most Australian guidance documentation on

contaminated site characterisation necessarily covers

the broad spectrum of chemical types used in Australia,

not just petroleum hydrocarbons. Also, in the past the

primary focus of guidance has often been soil

contamination, rather than groundwater impacts or indeed

vapour phase pathways. Few guidance documents

had considered in detail the multiphase behaviour of

petroleum hydrocarbons, or the complex mixture of the

many compounds that they represent. Exceptions were

those produced by the oil industry themselves, such as

the American Petroleum Institute (API).

Here we provide a brief description of some of the

guidance and protocol documentation available.

4.1 Australian guidance andstandards

4.1.1 National guidance – the NEPM

The ANZECC/NHMRC Guidelines for the Assessment

and Management of Contaminated Sites were released

in January 1992 (ANZECC/NHMRC 1992). These were

subsequently reviewed, updated and incorporated within

the NEPM (Assessment of Site Contamination) which

was formed in December 1999 (NEPC 1999a). This is

currently under review. It has specific sections devoted

to the investigation of petroleum hydrocarbon-

impacted sites.

The NEPM includes two schedules – Schedule A which

gives a general strategy for site investigation, and

Schedule B which provides particular sub-schedules

containing detailed guidance for site assessment.

Schedule A indicates that site assessment should

progress (as discussed earlier) in a staged way – from a

preliminary investigation involving data quality objectives,

site history, review of local geology and hydrogeology,

and establishing a sampling strategy and sampling pattern

for soil and groundwater etc., to a detailed investigation

which is required when the preliminary investigation

yields insufficient data for adequate site management.

Schedule B includes guidance on investigation levels,

data collection and sampling, laboratory analysis,

ecological and health risk assessments, community

consultation and more.

Schedule B(2) documents guidelines for data collection,

in particular sample design and reporting for soil and

groundwater. For soil sampling, reference is made to the

Australian Standard (AS 4482.1, 1997 – now AS 2005),

and to the need to consider ‘hot spot’ detection, site

history and other local factors. A weighting towards

shallow soil sampling is advised where ecological and

health risk assessments are required. Deeper sampling

to determine the nature and potential longevity of a

source of vapours moving through the soil profile is noted,

and deeper soil sampling may be required to appraise

the risks to groundwater. However, no specific guidance

or minimum set of samples is given. It is noted that

composite sampling is not recommended for health risk

assessments – a description of composite sampling is

4. Guidance and protocol documentation



provided in AS (2005), and it is described briefly below.

TPH carbon fraction analysis is recommended, and

separation into aliphatic and aromatic fractions is

suggested where site-specific quantitative health risk

assessment is required.

Schedule B(2) and Schedule B(6) describe groundwater

characterisation procedures, the latter related to a risk-

based assessment of groundwater contamination.

Schedule B(2) indicates that monitoring wells should be

installed to delineate the plume, but that delineation does

not necessarily mean defining the outer contour of the

plume – rather that downgradient wells show acceptably

low concentrations relative to near-source concentrations.

Vertical sampling is only mentioned in relation to targeting

the relevant zone for remediation, rather than for

compliance or risk assessment.

Under the current 2005–07 review of the NEPM,

specific issues were identified that related to petroleum

hydrocarbons. These issues are deemed to need

additional effort and investigation to provide updated

material for the revised NEPM document. Some of the

issues are listed below (NEPC 2006):

1. 2.3 Specific Substances:

2.3.1 Total Petroleum Hydrocarbons (TPH) –

Schedule B(1)

2.3.2 Fuel components – Schedule B(1)

2.3.5 Assessment of Impacts from Volatile

Substances – Schedule B(7a) & B(7b)

2. 2.4 Site Assessment:

2.4.1 Data Quality Objectives and Poor

Quality Site Investigations, including

Lack of Vertical Delineation and

Characterisation of Contamination –

Schedule B(2)

2.4.2 Groundwater assessment – Schedule

B(2) & B(6)

2.4.3 Assessment of fuel storage sites –

Schedule B(2)

3. 2.5 Laboratory methods and techniques:

2.5.1 Laboratory methods and techniques –

Schedule B(3)

Public and summary comment on the issues is available

in the NEPC (2006) document – but those related to

petroleum hydrocarbons are also reproduced in Appendix

A of this report.

4.1.2 NSW Department of Environmentand Conservation (NSW DEC)

Recognising the particular nature of petroleum

hydrocarbon fuels when released to the environment,

in 1994 the NSW EPA developed specific guidance for

assessing service station sites (NSW EPA 1994). This

guidance was developed in recognition of the increased

rationalisation of the number of service station sites by

the oil industry across Australia at the time. In the 1970s

the total number of operating service station sites was

estimated to be 20,000, and estimates in 1994 were that

the number of operating sites would be 6500 by the year

2000. The guidance was developed to be followed prior

to decommissioning of these sites and ultimate release

of the land for re-use.

The document provides overview guidance on

assessment, remediation and validation of the remediation

effort. It documents a minimum soil and groundwater

sampling protocol (numbers and locations), sampling and

handling procedures, analytes and analytical methods

required, and threshold concentrations for soil and

waters for particular analytes. The guidance also itemises

the costs of assessing and remediating a site, including

the additional costs based on the implementation of the

new guidance requirements – this amounted to an

increased cost of nearly 60%.

Whilst research and understanding has progressed

significantly since this time, within Australia the 1994

guidance was pioneering in providing explicit advice

related to petroleum spills at service station sites.

Minimum soil sampling included two samples per

underground storage tank (UST), two samples per UST

pit soils, one per pump station, one per fuel feed line,

two per below ground waste oil tanks and one sample

per 25 m2 for each above ground tank, spent battery

storage and waste disposal area, and one sample per

100 m2 for imported fill. Minimum groundwater sampling

included the installation of one borehole per contaminated

area on-site, one borehole downgradient and adjacent to

the site perimeter to check for off-site migration, and one

borehole upgradient and adjacent to the site perimeter

to act as a control location. The guidance indicates that

the sampling depth should be dictated by the

hydrogeological conditions.

NSW DEC (2004) also developed draft guidelines for

the assessment and management of groundwater

contamination.

4.1.3 Queensland Department ofEnvironment (Qld DoE)

The Queensland Department of Environment developed

draft guidelines for the assessment of contaminated sites

in May 1998 (Qld DoE 1998). This was immediately prior

to the development of the NEPM.

The main body of the guidelines largely provided an

overview of the legislation, governmental and other

responsibilities, notification and registration procedures,

and land assessment and remediation discussion. In

appendices some detail was provided on staged

investigations, and technical guidelines for site assessment

and remediation. The latter provided typical general

guidance on sampling and analysis and precautions that

should be taken to gain reliable data and understanding

for regulatory and remedial decision making. No specified

sampling density was indicated – the guidance relied on

the Australian Standards and suggested that:

‘The sampling programs should be designed on the

basis of site history investigations and site conditions.

Professional experience and judgment should be used

to ensure adequate coverage. Section 6, Design of

the Soil Sampling Strategy and Section 7, Sample

Collection, of Australian Standard AS4482 or the

equivalent NEPM guideline on data collection are

important references for sampling methodology.’

4.1.4 South Australian EPA

The South Australian EPA also developed guidance

related to the assessment of USTs (SA EPA 2005),

based on Cattlin and Fanning (2003). This recognised

the programs developed in the USA, and the ubiquitous

nature of underground storage systems (USS) across

Australia. The guidance promoted the NEPM approach

and referenced Australian Standard (AS4482.1 – AS

2005). They encouraged consideration of the entire site,

not just the UST/USS, and assessment of all past use

of a UST/USS, not just petroleum hydrocarbon storage.

They recognised the complexity of stipulating the number

of samples required. They suggest that the traditional

number of soil samples to be recovered – such as two

samples per pit floor, and one sample per wall of

excavation – may be adequate for smaller excavations,

but not for large pits or for hotspot identification. The

guide indicated that soils should be taken from (i)

immediately above any current or historic groundwater

level within the excavation, (ii) the intersection of the

backfill with the natural soil, (iii) the base of the tank pit

excavation, and (iv) beneath the USS to determine deeper

penetration of hydrocarbons. Interestingly the guide

requires that samples not be recovered (and presumably

bulked) from a depth interval greater than 100 mm.

The guide suggests before assessment of groundwater

for contamination that the following should be investigated:

(i) the products stored at the site and breakdown products,

(ii) mobility, (iii) site hydrogeology, (iv) potential for

preferential flow, (v) potential for groundwater mounding

and radial flow, (vi) bedrock type, (vii) potential infiltration

to deeper aquifers, (vii) plunging groundwater plumes,

and (viii) potential for the presence of either light or dense

NAPL. It could be argued that these be considered in an

initial site conceptual model and before any initial soil or

groundwater investigation is undertaken.

Nonetheless, the delineation of the lateral and vertical

extent of the contamination was required.

4.1.5 Victoria EPA

EPA Victoria (2003) provides guidelines on the design,

installation and management for underground petroleum

storage systems (UPSS). However, this provides no

detailed site assessment guidance for petroleum

hydrocarbon-impacted sites. EPA Victoria (2002) includes

descriptions related to petroleum-related pollution and

NAPLs. EPA Victoria (2002) provides overview direction

on the need to characterise groundwater impacts to

assess the nature, extent and degree of pollution. The

note suggests collecting data to define geology and

hydrogeology, including spatial and temporal variations

in flow parameters, and spatial and temporal distributions

of the extent and nature of contaminant distributions –

including partitioning between groundwater, aquifer

materials and gas and contaminant transformation

processes and transformation rates and sorption

capacities. The practicability of clean-up of polluted

groundwater is also discussed in this bulletin, which takes

account of technical, logistical and financial considerations.

4.1.6 Western Australian Department of Environment and Conservation(WA DEC)

The Western Australian Department of Environmental

Protection (now the Department of Environment and

Conservation or DEC) produced guidance on the

Development of Sampling and Analysis Programs in

December 2001. This embodied previously developed





guidelines entitled the Guideline for the Assessment of

Sites Incorporating Underground Storage Tanks and

Contaminated Site Assessment Guidelines for the

Development of Sampling and Analysis Programs. WA

DEP (2001) promotes a staged approach: Stage 1 –

Preliminary Site Investigation (PSI); Stage 2 – Detailed

Site Investigation (DSI); Stage 3 – Site Management Plan

(SMP) and Stage 4 – Remediation Validation and Ongoing

Management. It sought to integrate knowledge and

understanding at the time, and provided specific guidance

related to the design of a soil, sediment and groundwater

sampling and analysis program, QA/QC, and validation

sampling design. It suggests the number and likely

location of soil and groundwater sampling.

For soils at a UST it specifies that a minimum of two

samples be recovered per tank, five per UST pit, plus

three per additional UST in the same pit, 1–2 around

pumps and fuel lines, and ‘some’ for imported fill and

stockpiled material. In addition, for soils it specifies that

determining the vertical extent of contamination is

important and that soil samples should be collected from

more than one depth – especially to delineate the furthest

depth of penetration of impact. No total minimum

number of samples is stipulated. For groundwater, a

minimum of three wells are recommended to be drilled

to triangulate groundwater flow directions local to the

site. Additional bores are recommended so the ‘areal

extent of the pollution plume can be identified’.

4.1.7 Australian Standards

There are three main Australian Standards that relate

to contaminated site characterisation. These are:

• Guide to the investigation and sampling of sites with

potentially contaminated soil. Part 1: Non-volatile and

semi-volatile compounds, AS 4482.1-2005 (AS 2005)

• Guide to the sampling and investigation of potentially

contaminated soil. Part 2: Volatile substances,

AS 4482.2-1999 (AS 1999)

• Water quality – Sampling. Part 11: Guidance on

sampling of groundwaters, AS/NZS 5667.11:1998

(ISO 56667-11:1993) (AS/NZS 1998).

AS (2005) provides a general framework and techniques

for sampling soils – including some discussion of data

quality objectives (US EPA 2006). It describes the process

by which a soil investigation should be developed and

reported, and provides some general guidance on

sampling strategies to capture uncertain distributions of

contaminants. This standard also describes a procedure

for composite sampling of soils – that is mixing soil

samples taken from multiple locations at a site prior to

sub-sampling for analysis. It is recommended that the

investigation or threshold limit be divided by the number

of soil samples that are included in the mix.

AS (1999) provides more detail on the precautions that

may be necessary for reliable sampling of volatile

compounds in soils, including soil gas and soil sampling

protocols. The standard cautions against contact of

samples with atmospheric air, and outlines zero headspace

and solvent extraction procedures.

AS/NZS (1998) provides guidance on the sampling of

groundwater to determine groundwater quality. It describes

the types of boreholes and sampling techniques, and

refers to guidance on sample handling and preservation.

Some comment is provided on the need for the optimal

number of bores to satisfy the sampling objectives but

no information is provided to determine the number or

location, although reference is given to ISO 5667-1 which

provides a description of the application of statistical

techniques to define sampling density. Depth profiling

within the groundwater is described as desirable

(‘provision should be made for sampling from a range

of depths’) and preference is noted to have at least one

borehole screened across the water table to capture

shallow contaminant impacts. Particular needs for

dispersed sources versus point sources of contamination

are described.

For petroleum contamination all three standards would

be applicable, although no particular Australian standard

seems to be available for sampling volatiles in groundwater.

The soil standards do not provide guidance on depth

profiling of soil contamination, which may be important

where petroleum hydrocarbons have penetrated to

significant depths through the vadose zone or where the

NAPL smear zone is large due to water table fluctuations.

4.2 Overseas guidance,standards and information

4.2.1 US EPA

The US EPA Code of Federal Regulations (CFR)

embodies a broad range of regulations and 40 CFR Parts

280 and 281 cover most of the regulations related to

underground storage tanks (USTs), although information

related to state and territorial programs is found elsewhere

in 40 CFR, as is a list of hazardous substances.

Subpart F of US EPA 40 CFR 280 documents the

required release response and corrective action for UST

systems containing petroleum or hazardous substances.

This provides a process by which an operator or owner

of a site must respond to the occurrence of a petroleum

hydrocarbon release or presence on their site. It does not

specify what type of samples to recover or methods to

adopt to achieve good site characterisation, nor does it

give references to guidelines or procedures. Nonetheless,

it provides overview guidance and forms part of mandatory

response needs in such circumstances.

Additionally, the US EPA has developed a broad range

of guidance documentation on sampling and assessment

techniques and technologies – one example is a

compilation of site characterisation techniques (see

US EPA 2003).

Additionally the US EPA developed guidance on expedited

site assessment tools for underground storage tank sites

(US EPA 1997).

4.2.2 ASTM

ASTM (1995) is the US standard guide for risk-based

corrective action applied at petroleum release sites

(RBCA). It was developed by the American Society for

Testing and Materials (ASTM) in response to the need to

prioritise action at an overwhelming number of petroleum

release sites. The guidance sought to establish a tiered

approach to site characterisation and possible remediation

based on the use of threshold values that may dictate

additional or no further action at a petroleum-impacted site.

The approach sought to account for all potential

exposures and risks, and so eliminate some sites from

further investigation while focusing efforts where threshold

values and risks were exceeded and unacceptable. This

was termed risk-based corrective action (RBCA) – since

the risk became the driver of the decision for further action

and possibly remediation rather than default values for

soils and groundwater. In essence the approach required

the development of alternative and more specific

(although not necessarily site-specific) threshold values

for action based on modelled exposure pathways, default

parameters, aquifer/soil type, land use and other

assumptions.

ASTM (1998 and re-approved in 2004) is the standard

guide for accelerated site characterisation for confirmed

or suspected petroleum releases and was developed by

ASTM in response to the need to accelerate and expedite

site characterisation. The standard emphasises the need

to integrate rapid sampling and field analysis techniques

with on-site interpretation and iteration of field data to

update and improve the site conceptual model as

characterisation proceeds – with the ultimate aim to

improve the process to allow a single mobilisation for site

characterisation. The standard provides a description

of the overall approach – some of the field sampling and

analytical techniques and importantly provides some

examples of its application for Tier 1 and 2 assessments.

No significant detail is provided on preferred techniques

that should be used in an ASC program.

4.2.3 United Kingdom

There does not seem to be specific guidance available

for the UK on petroleum-impacted land. Instead there

is a hierarchy of documentation from changes to the

Contaminated Land Act, to management procedures for

regulators, through to British Standards. In September

2006, the updated Contaminated Land portion of the

United Kingdom Environmental Protection Act 1990;

Part 2A (DEFRA 2006) came into being. This was the

culmination of a long process to ensure liability and

accountability was attributable for contaminated land

issues, although it seems a form of the Act was in place

in 2000.

The Contaminated Land part of the Act was risk-based

and indicates that the risks on each site are to be

assessed, and the controls are triggered only where

there is significant harm, or a significant possibility of it,

or actual or likely pollution of controlled waters. The

extent of the risk on any particular land depends upon

a number of site-specific factors including the following:

• the characteristics of the substances in the land

• the local geology and hydrogeology

• the nature and presence of receptors

• the use of the land, or of adjacent land

• the nature of the land, in terms of whether pathways

might exist or be created

• what measures exist, if any, to reduce or limit the risk.

Two technical guidance documents were released by

UK EA (2000a, 2000b), and there is a British Standard

(BSI 2001) which outlines the code of practice for the

investigation of potentially contaminated sites. In

addition, UK EA (2004) was published to provide a

technical framework for structured decision making

related to land contamination. These and others provide

a general cluster of general technical guidance related

to land contamination. There seems to be no one location





where all documentation can be obtained at once – it is

distributed between the Department of Environment, Food

and Rural Affairs (DEFRA), the UK Environment Agency

(UK EA) and previous agencies, and British Standards.

The UK EA (2000a, 2000b) documents are intended

to provide guidance to EA staff who are involved in the

management of site investigation projects. As such these,

and UK EA (2004) to some extent, deal with higher level

issues of structured decision making and consultant/

contractor management. These documents primarily

relate to the assessment of greater levels of detail in risk

definition and progress from risk identification, hazard

assessment, to risk estimation and evaluation. These

deal with the conceptual model, information

requirements, degree of confidence and uncertainties,

and criteria for judging the acceptability of risks. UK EA

(2004) proposes:

• preliminary risk assessment which may involve desk

study, site reconnaissance, additional desk study

or exploration

• generic quantitative risk assessment which may involve

use of generic criteria, intrusive site investigations,

supplementary site investigations and review, and

• detailed quantitative risk assessment which involves

site-specific assessment criteria derived from site-

specific information on the behaviour of contaminants,

pathways and receptors, and relevant criteria related

to ‘harm’ or unacceptable risk.

These three ‘risk definition’ steps use a different language

but largely parallel tiered approaches as defined by others.

BS (2001) contains technical advice on the design and

implementation of site characterisation (including intrusive

site investigation) activities for contaminated land. It

focuses on the selection and use of different field sampling

and monitoring techniques, collection, handling and

transport of samples, and reporting of field observations

and related data. Much of the underlying guidance on

sampling and handling of samples for analysis is contained

in other referenced standards, e.g. BS 6068-6.11

provides guidance on the sampling of groundwaters. Note

that BS 6068-6.11, ISO 5667-11:1993, and AS/NZS

5667.11:1998 (AS/NZS 1998) are technically equivalent

and have been reproduced from each other.

In BS (2001) the usual stages of investigation are proposed

– preliminary, main and supplementary investigations.

Possible sampling strategies are described, along with the

advantages and disadvantages of a range of investigation

techniques. The standard notes the ‘averaging’ nature of

soil gas and groundwater samples in comparison to soil

samples which may be more variable at point scale due

to soil heterogeneity. The standard suggests soil

sampling densities from 20–25 m to 50–100 m centres,

with vertical resolution from ground surface, 0.1 m, 0.5 m

and other depths up to 1 m intervals in natural ground.

The standard notes that these spacings will depend on

site contamination circumstances and the intent of the

investigation. The standard recommends that composite

sampling not be carried out – in contrast to the Australian

Standard (AS 2005). For groundwater investigations, BS

(2001) advises a preference for at least one borehole to

be screened across the water table to capture LNAPL

if present – and then advises reference to BS 6068-6:11

(equivalent to AS/NZS 1998 – summary comment on

AS/NZS (1998) was given earlier). BS (2001) also has a

sizeable discussion on soil gas sampling, density, depths

and its uses – and a section on the use of soil gas

sampling for VOCs.

4.2.4 Europe and NICOLE

Ferguson et al. (1998), Ferguson and Kasamas (1999)

and Ferguson (1999) summarise risk assessment policy

and procedures for contaminated sites in Europe, under

the CARACAS and CLARINET program of activity (see

http://www.clarinet.at/). CLARINET was the Contaminated

Land Rehabilitation Network for Environmental Technologies

in Europe, which ceased active work in June 2001.

CARACAS was the Concerted Action Initiative on Risk

Assessment for Contaminated Sites, active from 1996–98.

The books by Ferguson contain a section on site

investigation and analysis as practised across Europe

at that time. Most countries’ policies reviewed indicated

a staged approach to site investigations – and some

indicated the importance of a site conceptual model to

guide field investigations. In nearly all cases a risk-based

approach had been adopted, and investigation or trigger

value concentrations for soils in particular were being

developed to determine the need for further investigation

and assessment. Details on preferred site investigation

technologies could not be sourced easily.

For groundwater, the regulations were also largely

concentration based (e.g. Bundes-Bodenschutz- und

Altlastenverordnung (BBodSchV) in Germany). A notable

exception may be the state of Baden-Wurttemburg –

when characterising the monitored natural attenuation

potential of a groundwater plume, both concentration

and mass flux are taken into consideration

(Gemeinsame Verwaltungsvorschrift des Ministeriums für

Umwelt und Verkehr und des Sozialministeriums über

Orientierungswerte für die Bearbeitung von Altlasten und

Schadensfällen). In this case, assessment may target the

distribution of concentrations within a groundwater plume

to ensure compliance, but alternatively could target the

mass flux into the receiving environment or beyond some

compliance point to satisfy regulatory requirements.

NICOLE (Network for Industrially Contaminated Land

in Europe) was set up in 1995 to promote cooperation

between industry and academia on all aspects of

contaminated land in Europe. In April 2002 and May

2006 NICOLE convened workshops focused on site

characterisation, and in particular it looked at how site

characterisation might be made more efficient (NICOLE

2002) and how it supported conceptual site model

improvement (NICOLE 2006).

The 2002 meeting sought to balance the cost of

acquiring additional data against the depth of knowledge

necessary to manage contamination risks. It recognised

that insufficient site characterisation could ultimately lead

to higher overall site management costs due to poor risk

management and planning. Conversely it noted that

excessive site characterisation may add unnecessary

costs for what might be redundant additional information.

Legislation was seen as a pressure that drove the cost

curve upwards, while technical innovation to enhance the

efficiency of site characterisation was seen as a pressure

that could drive the cost curve downwards. Van Ree and

Carlon (2003) summarised some elements of the meeting.

NICOLE (2006) was focused on data collection activities

that are required to develop a good conceptual site model.

The workshop supported the conclusions from NICOLE

(2002) and also noted apparent barriers to technology

uptake. They indicated a need to develop ‘mechanisms’

to move site investigation technology from the theoretical

development stage, through the pioneering study stage

to acceptance on an industry-wide scale. The latter may

be, for example, the provision of guidance. They proposed

several possible courses of action:

• initiate dialogue with industry and regulatory bodies

with a view to developing a framework for technology

testing and approval

• support an effective monitoring and testing program

for new technologies that is widely accepted by all

interested parties

• support the development of monitoring guidelines for

the comparison of technologies so that appropriate

technology can be selected on a fitness for purpose

and cost-effectiveness basis

• emphasise the importance not only of improved data

quality (in terms of cost, speed and ease of use) but

also of improved use of data in terms of developing

good quality site conceptual models

• support training in and dissemination of advances

in site characterisation techniques amongst service

providers and regulators.

4.2.5 New Zealand Ministry for theEnvironment (NZ MfE)

New Zealand has a number of guidance documents –

some of which are specific to the assessment and

management of petroleum-impacted sites, e.g. NZ MfE

(1999a, 1999b). NZ MfE (1999a) provides specific draft

guidance on the sampling protocols and analytical

methods for determining petroleum products in soil and

water. NZ MfE (1999b) consists of seven modules (or

documents) that relate to a Tier 1 assessment of soils

and groundwater impacted by petroleum hydrocarbons,

and the development of site-specific acceptance criteria

where needed. One module provides guidance on

suitable methods of site investigation, including information

on the design of a sampling program, the suitability

of various types of investigation equipment, sampling

techniques, and quality assurance. This includes the

general strategies of conducting a desk study, site

reconnaissance, building the conceptual model, and

design and implementation of a more detailed investigation

program. This module tabulates a recommended

minimum number of soil samples for a site – and includes

collecting five samples per underground storage tank pit,

one per bowser island, one per 5 m of underground line,

one per 10 m of above ground fuel line, one per 25 m2 in

drum storage and cleaning areas, one per 25 m2 in used

battery storage area, one per 25 m2 in waste disposal

areas, one per 25 m2 of wall areas in general excavations,

and for general borehole drilling collect five per borehole

at fixed intervals (e.g. 0.3 to 1.5 metres), and at any

change in lithology, and any other depth at which impact

is observed or measured.

For groundwater investigations a minimum of three wells

is proposed to triangulate flows and for sampling, but the

‘sampling plan may need to be modified to include

additional sampling points to determine the extent of the

contamination’. No additional specific guidance is offered

related to sampling with depth – although it is stated that

‘well locations and completion depths must be selected

to ensure that all probable petroleum hydrocarbon flow

paths are monitored’. Quarterly or semi-annual monitoring





is proposed in the first year in recognition of the potential

variations in groundwater conditions due to seasonal

trends and recharge events.

Similar guidance to NZ MfE (1999b) in an Australian

context was reported by AIP (1999) and Cerneaz (1999).

NZ MfE (2004) describes the principles of how to plan

and conduct investigations, and sets out best practice

that should be followed for sampling and analysing soils

on sites where hazardous substances are present or

suspected. It discusses the importance of the site

conceptual model and data quality objectives (DQOs)

when planning an investigation. It provides specific

guidance related to volatiles in soils. Strategies for

planning the sample density and number of samples are

given, depending on investigation objectives and likely

site contamination.

Table 2. Industry, government and other site assessment protocols

Agency Title Comment

Australian

NEPC National Environmental Protection (Assessment of Site Contamination) This is currently

Measure 1999. under review

NSW DEC NSW EPA, Guidelines for assessing service station sites, 1994, 30 pp. Specific to USTs

NSW DEC, Draft guidelines for the assessment and management of

groundwater contamination, December 2004, 48 pp.

Qld DoE Draft Guidelines for the Assessment and Management of Contaminated Developed prior

Land in Queensland, May 1998, 80 pp. to the NEPM

SA EPA EPA 580/05, Assessment of Underground Storage Systems, February Specific to USTs

2005, 10 pp.

Vic EPA EPA Victoria, Guidelines on the Design, Installation and Management for Specific to petroleum

Underground Petroleum Storage Systems (UPSS), Publication 888, 2003, UST design and

Environment Protection Authority, Melbourne. leak detection

EPA Victoria, The clean up and management of polluted groundwater,

Publication 840, April 2002, 16 pp.

WA DEC Department of Environmental Protection. Development of Sampling and

Analysis Programs (Guideline for the Assessment of Sites Incorporating

Underground Storage Tanks and Contaminated Site Assessment Guidelines

for the Development of Sampling and Analysis Programs as amended),

Contaminated Sites Management Series, December 2001, 77 pp.

Standards AS 4482.1-2005: Guide to the investigation and sampling of sites with

Australia potentially contaminated soil. Part 1: Non-volatile and semi-volatile compounds.

AS 4482.2-1999: Guide to the sampling and investigation of potentially

contaminated soil. Part 2: Volatile substances.

AS/NZS 5667.11:1998 (ISO 56667-11:1993): Water quality – Sampling.

Part 11: Guidance on sampling of groundwaters.

Overseas

ASTM ASTM E1739-95: Standard guide for risk-based corrective action applied Specific to petroleum

at petroleum release sites (RBCA). USTs

ASTM E1912-98 (re-approved in 2004): Standard guide for accelerated site

characterization for confirmed or suspected petroleum releases.




Overseas (cont.)

US EPA US EPA Code of Federal Regulations (CFR) – Part 280 (40 CFR 280): Specific to USTs

Technical standards and corrective action requirements for owners and

operators of underground storage tanks (UST).

US EPA Code of Federal Regulations (CFR) – Part 281 (40 CFR 281): Specific to USTs

Approval of state underground storage tank programs.

EPA 510-B-97-001: Expedited site assessment tools for underground Specific to USTs

storage tank sites – a guide for regulators.

Numerous additional published materials are available from US EPA –

especially through the Office of Underground Storage Tanks within the

Office of Solid Waste and Emergency Response (OSWER).

UK UK Department of Environment, Food and Rural Affairs, Environmental

Protection Act 1990, Part 2A Contaminated Land. DEFRA Circular

01/2006, September 2006, 200 pp.

UK EA, Technical aspects of site investigation. Volume I (of II): Overview,

Research and Development: Technical Report P5-065/TR, UK Environment

Agency (JE Steeds, NJ Slade and MW Reed), 2000, 101 pp.

UK EA, Technical aspects of site investigation. Volume II (of II): Text

supplements, Research and Development: Technical Report P5-065/TR, UK

Environment Agency (JE Steeds, NJ Slade and MW Reed), 2000, 181 pp.

British Standard, Investigation of potentially contaminated sites, Code

of Practice, BS 10175: 2001, 82 pp.

UK EA, Model Procedures for the Management of Land Contamination.

Contaminate Land Report 11, September 2004, 203 pp.

Europe Ferguson, CC, Darmendrail, D, Freier, K, Jensen, BK, Jensen, J, Kasamas,

(General) H, Urzelai, A & Vegter, J (eds) 1998, Risk Assessment for Contaminated Sites

in Europe. Volume 1 – Scientific Basis. LQM Press, Nottingham.

Ferguson, C & Kasamas, H (eds) 1999, Risk Assessment for Contaminated

Sites in Europe, Volume 2 – Policy Frameworks. LQM Press, Nottingham.

NICOLE 2002, Cost-effective site characterisation – dealing with uncertainties,

innovation, legislation constraints, Summary of Nicole Workshop, 18-19 April

2002, CNR, Pisa, Italy.

NICOLE 2006, Data acquisition for a good conceptual site model, Report

of the NICOLE Workshop, 10-12 May 2006, Carcassonne, France, 42 pp.

New Zealand NZ MfE, Guidelines for Assessing and Managing Petroleum Hydrocarbon Specific to petroleum

Ministry for the Contaminated Sites in New Zealand, New Zealand Ministry for the

Environment Environment, 1999.

NZ MfE, Contaminated Land Management Guidelines No.5: Site Investigation

and Analysis of Soils, February 2004, ME497, 93 pp.

NZ MfE, Draft Sampling Protocols and Analytical Methods for Determining Specific to petroleum

Petroleum Products in Soil and Water, May 1999, Ref. ME613, 59 pp.

Table 2. (cont.) Industry, government and other site assessment protocols



4.3 Industry guidance andprocedures

4.3.1 American Petroleum Institute(API)

API has published two main guidelines related to the

characterisation and corrective action for petroleum

release sites, namely API Publication 1628 and 1629

(API 1993 and API 1996 respectively). API (1996) was

published as a second edition in 1989 and as a third

edition in 1996. API (1993) has had only one edition.

API (1993) focuses solely on soils, and provides companion

information for API (1996). In particular it provides a

summary of:

• the interaction of hydrocarbons with soils

• emergency response procedures

• site assessment procedures

• sampling and analysis techniques

• corrective action options, including a summary

of a range of remediation options.

API (1996) takes a more holistic view of a petroleum

release including assessment and remedial options for

a petroleum release to both groundwater and soil

environments. It includes:

• an overview of soil/aquifer and hydrocarbon properties

• a discussion of the ASTM RBCA approach

• initial emergency response procedures for a spill

• methods used to assess the distribution and potential

migration of the phases

• risk assessment principles, and

• control and remediation options.

API (1996) provides information and technologies for (i)

soil sampling, (ii) LNAPL thickness monitoring and analysis,

(iii) dissolved phase investigations, and (iv) vapour phase

investigations.

The rationale as to the number and location of soil

samples is given in API (1993). Where the approximate

location of the source is known, it is recommended that

samples be taken from near the source and at successive

distances away from the source until background

conditions are found. Of course the direction of movement


Industry

Company A Remediation Management Asia Pacific Guidelines, Revision C, June 2005, A compendium of

151 pp. inter-related guidelines

Company B 1.Technical Specification: Module 2 – Phase 1 Environmental Site Assessment,

June 2006, 39 pp.

2. Environmental Site Assessment specification: Module 3 – Phase 2

Environmental Site Assessment, June 2006, 124 pp.

Company C Specification for Environmental Site Investigation Services (ESIS), June 2003,

84 pp.

Company D Environmental Standards Hazardous Material and Contamination Control,

September 2003, 3 pp.

Environmental Standards – Contaminated Land Assessment & Remediation

Guidance Note: Version 2.1, September 2004, 35 pp.

American API Publication 1628: A Guide to the Assessment and Remediation of No updates seem to

Petroleum Underground Petroleum Releases, Third Edition, July 1996, 119 pp. be available since

Institute 1996

API Publication 1629: Guideline for Assessing and Remediating Petroleum No updates seem to

Hydrocarbons in Soils, First Edition, October 1993, 81 pp. be available since

1993

Table 2. (cont.) Industry, government and other site assessment protocols

Two modules

depending on the

level of assessment

required

and extent are rarely known a priori. Where the source

location is unknown then regular grid sampling is

described as an option with samples to be recovered at

3–30 m spacings. The vertical interval for soil sampling

is given as 1.5 m through the vadose zone until ground-

water is reached or hydrocarbon concentrations decrease

to background. No detail or statistical analysis is provided

as guidance on actual spacings and numbers of samples

(cf., for example, AS 2005). API (1996) provides no

additional information on the soil sampling strategy.

API (1996) provides a traditional view of the number of

groundwater wells – a minimum number of three wells

to establish a groundwater flow gradient and at least

one of these being upgradient. It is noted that additional

locations may be required to delineate any plume that

is present, and depth issues are recognised as needing

consideration based on hydrogeology and other issues,

but no further guidance on the number and frequency

of sampling is given.

Despite this, both of the API documents indicate the

need to delineate the distribution of hydrocarbons in all

phases adequately, and explicitly states the need for

delineation in three dimensions for some phases.

Although a little dated, the API documents provide an

extensive amount of useful information, including fuel and

oil properties, drilling techniques for different geological

environments, sampling and analytical techniques, and

a description of some remedial options. Interestingly,

both guidance documents include a description of and

guidance on remediation options.

4.3.2 Company A

Company A (2005) provides a cluster of readable guidance

documents – arranged as discrete guidance notes – and

largely designed for internal Company A use. These are

then referenced or grouped for tackling larger tasks as

part of a site characterisation. The guidance manual (i)

states that it ‘shall only be used by professionals who have

experience in the field of contaminated site assessment

and remediation’, (ii) is only a minimum set of standards

for Company A, and (iii) recognises that legislation,

guidelines and standards will change.

Company A (2005) divides sites into two broad

categories – low impact potential (LIP) sites and high

impact potential (HIP) sites – based on significant impact.

The guidelines describe a minimal sampling regime that

will be carried out at sites, and if significant impact is

determined at a LIP category site, this then is placed in

the HIP category for further assessment. Assessment of

HIP category sites may be pursued via accelerated site

characterisation protocols (ASTM 1998), the aim being

to gather data in a single mobilisation for such sites.

Guidance is provided for soil, NAPL and water phases.

Vapour assessment is targeted at potential exposures

and risks to human health, rather than as a tool for

remote detection of subsurface contamination. Minimum

soil sampling locations includes one per UST, one per

line trench, one per dispenser, two per above ground

storage tank, one per storage location and one background

location. The guidance also provides some comment on

sampling related to the scale of the site – it provides a

tabulation of the recommended number of sampling

points for variable size sites. For example, for a 0.05 ha

site a minimum number of sample locations is five based

on detecting a 12 m diameter hotspot, whereas for a 5 ha

site it is recommended that a minimum of 55 locations

be sampled to detect a hotspot of diameter 36 m or

greater. Groundwater is to be monitored at a minimum of

three locations (one upgradient and two downgradient of

potential on-site sources) where groundwater is present

within 8 m of the site surface, or where beneficial use of

groundwater occurs within 1 km of the site. Additional

wells should be installed to ensure delineation of impact,

where high levels of impact are detected.

The guideline also tabulates soil assessment/threshold

values for New South Wales, Western Australia,

Queensland and national values found in the NEPM,

and water quality assessment criteria. Possible remedial

strategies are listed without discussion of the relative

advantage or disadvantage of any one technology.

4.3.3 Company B

Company B (2006a, 2006b) provide specifications for

environmental site assessment for Phase 1 environmental

site assessment (Company B 2006a) and Phase 2

environmental site assessment (Company B 2006b).

Phase 1 consists primarily of collation of site background,

its setting, historic data and a receptor survey. This provides

input into the Phase 2 assessment which proceeds to

field investigations. The specifications emphasise the

need to consider data quality objectives as described

in AS (2005) – i.e. an assessment of the need for, and

purpose of, any and all data collected.

Company B (2006b) provides a tabulation of soil borings,

soil gas sampling, and groundwater wells required –

and these are separately itemised based on land





transaction or operational issues (e.g. divestment,

acquisition, lease or operational). At one level, one

sample per bore is suggested where there is no field

evidence of contamination, but where contamination is

present soil samples are to be taken within, above and

below the impacted zone to map its vertical extent –

from 0–0.1 m, 0.5 m, 1m (and every metre to 8 m) and

then every 2 m beyond that. The number of soil boring

locations may range from 2.5 to 10 per 0.1 ha.

Four groundwater investigation wells are suggested –

with one upgradient and three targeting the source areas.

In many cases, site-specific numbers and quantities are

suggested. Soil gas sampling is proposed to assist with

contamination mapping. NAPL baildown tests are

mentioned as a means of characterising mobile NAPL

and refers to Gruszczenski (1987).

Soil assessment guidelines/criteria are listed from NSW

EPA (1994), NEPC (1999a), ANZECC/ARMCANZ (2000)

and AIP (1999), and it is noted that some states may

require different analyses on samples.

4.3.4 Company C

Company C (2003) describes specifications for

environmental site investigation services (ESIS). The

specifications are largely designed for joint Company

C/contractor involvement in the stages of investigation,

compared to say Company A (2005) which is largely

for internal Company A use. As such, in places the

Company C (2003) specification is more directive toward

required tasks (‘shall’), or provides advice to consultants

(‘should’), or provides options (‘may’).

The specifications are based on a staged approach, and

have a strong focus on the conceptual site model (CSM).

The stated objective of the field program is to validate

and/or improve the CSM.

Soil, soil gas and groundwater sampling is proposed. No

minimum spacing/density of soil sampling is specified,

but the specification provides some overall guidance and

indicates that sampling from impacted zones (laterally

or vertically) is to be continued at a site until no impact

is determined. No sample composting (see AS 2005) is

recommended for samples for VOC or SVOC analyses.

Minimum groundwater well installations are stated as

one well in the highest soil impacted zone, one well in an

upgradient location, and two wells near site boundaries

in the inferred downgradient flow direction. Soil gas

sampling as proposed in the specification is to assist

with source zone identification and possible pathway

exposure – but is not to be used for quantitative health

risk assessment purposes.

4.3.5 Company D

Company D’s guidance documentation is not specific

to petroleum hydrocarbons, and does not seek to list

details of the preferred techniques and methods to use

in site characterisation. Company D (2003) provides

a concise list of obligations that are seen as needing

compliance related to hazardous material control.

Company D (2004) provides greater detail and examples

on how to meet the obligations related to assessment

and remediation of contaminated land as outlined in

Company D (2003). Other guidance notes deal with

obligations related to hazardous materials handling,

non-mineral waste management, etc.

Company D (2004) includes a requirement to carry out

a screening and ranking of sites under a risk-based

assessment process as part of an ongoing planning

phase; as part of this, to maintain a contaminated sites

register; to carry out site assessments under a tiered

approach where the potential for contamination has been

identified; to develop and implement site management

plans where unacceptable impacts have been determined;

and by monitoring performance to ensure remediation

goals are being met.

The guidelines emphasise the need for the development

of risk profiles for chemicals of concern so as to prioritise

the allocation of resources for management and the tiered

risk-based approach. The guidance recognises that for

larger, more complex sites increasingly detailed levels

of investigation may be required separated by decision

points to evaluate the need for further investigation.

The Guidance Note includes a recommended general

risk assessment process for site contamination including

a trigger for assessment, a preliminary investigation,

a detailed site investigation, a modified risk-based corrective

action (RBCA) flowchart, and a proforma exposure

pathway analysis. Examples are given on the use of the

Guidance Note – related to petroleum hydrocarbon-

impacted sites and metals in fill/soil.

An abbreviated listing and discussion of some relevant

technology areas is given here, primarily focused on

rapid site characterisation technologies and those that

are somewhat new or non-standard. See also the many

resources available through the US EPA (e.g. US EPA

2003), ASTM (e.g. ASTM 1994) and other agencies, and

many textbooks (e.g. Boulding & Ginn 2004; Sara 2003).

5.1 Rapid site characterisationRapid or accelerated site characterisation tools include

direct push techniques, geophysics, soil gas surveys,

and improved on-line or on-site monitoring or analytics.

Van Ree and Carlon (2003) summarise the capabilities

and advantages and disadvantages of a number of

characterisation techniques. Their tabulation is

reproduced (with permission) in Table 3.

5.1.1 Direct push techniques

Direct push rigs are sometimes termed geoprobes or

cone penetrometers. Where site conditions allow direct

pushing of spear rods into the ground, a number of

measurement devices and increasingly on-board field

analysis can be simultaneously employed to aid with

rapid site characterisation. Such rigs can be used for soil

coring, soil gas and groundwater sampling, geophysical

measurements (e.g. friction (piezocone), conductivity,

nuclear logging), and sometimes deployed with

chemical sensors.

One example of combined techniques is the membrane

interface geoprobe – whereby the cone of the push rod

houses a semi-permeable membrane in a heating block.

Heating of the membrane induces volatile compounds in

the soil to rapidly diffuse across the membrane to an

internal gas phase which carries the analyte to an on-line

detector for measurement. The most commonly used

detectors include photoionisation detector (PID), electron

capture detector (ECD) and the flame ionisation detector

(FID). The detector type used will depend on the type

of volatile compound being investigated.

In situ measurement of organic compounds dissolved

in groundwater has also been accomplished using fibre

optic chemical sensors (Klainer et al. 1988; Milanovich

1986). These sensors pass light of an appropriate

wavelength to the measurement point by optical fibre.

The fibre is terminated with a chemical sensor; interaction

of the sensor with a target organic molecule changes

fluorescence, absorption or reflectance. Optical couplers

at the surface are able to separate reflected light from

excitation light, and this is analysed using a spectrometer

at the surface. Complex mixtures can be problematic for

fibre optic chemical sensors.

For either situation, as the probe is pushed the geoprobe

provides the potential to determine stratigraphic changes

from on-board probe geophysics, but can also capture

changes in chemistry with depth.

A good reference on cone penetrometer testing is Lunne

et al. (1997), which includes a chapter on environmental

geoprobing.

5.1.2 Geophysics

Surface geophysical techniques can be deployed and

interpreted quickly – if sophisticated software/hardware

capabilities are also available. The breadth of techniques

and possible applications is large, and many references

on method operation, selection and usefulness are

available. Greenhouse and Monier-Williams (1985) itemised

important considerations when selecting a geophysical

technique for a task, Boulding (1993a) provides systematic

information on potential applications with comparative

advantages and disadvantages, and Boulding (1993b)

provides a compilation of journal and conference paper

citations that have specific applications of methods.

Common techniques include ground-penetrating radar,

metal detection (transient electromagnetics or TEM),

magnetometry and electromagnetic methods, which have

been used for locating buried objects at sites. Seismic

refraction, electromagnetic methods, ground-penetrating

radar and electrical resistivity have been used for assessing

geological, hydrogeological and sometimes groundwater

contamination conditions – refer to Barber et al. (1991) and

Merrick (1997) for TEM and resistivity. Ground-penetrating

radar (GPR) and electrical resistivity have been used for

delineating residual or floating product – refer to Kelly

and Acworth (1994) for GPR. Downhole or direct push

technologies also incorporate geophysics (as indicated

above) and this is being increasingly utilised. Although

other downhole geophysics is commonly used this may


5. Sampling and investigation technologies

not be ‘rapid’, as pre-drilling of purpose-built piezometers

may be required.

There continues to be significant activity related to the

potential use of geophysics to map dense non-aqueous

phase liquids (DNAPLS) in the subsurface. These may also

be applicable for LNAPLs. A method that holds significant

promise is complex resistivity, which has discriminatory

information content in its phase spectrum (Borner et al.

1993; Olhoeft 1985). Laboratory detection seems to be

validated, but field detection is not convincing (Brown

et al. 2003; Olhoeft & Fiore 1999). Tomographic complex

resistivity could be more definitive for successful field

application, but then the method would no longer be

rapid (Daily & Ramirez 1995; Ramirez et al. 1996).

On occasion, electrical and electromagnetic methods

may not be applicable at contaminated sites because

they are sensitive to electrical interference from power

lines, metal pipes and grounded metal structures.

5.1.3 Soil gas surveys

Soil gas surveys are sometimes promoted to expedite

investigations to map the occurrence or distribution of

deeper hydrocarbon contamination. The strategy is to

push a spear probe into the shallow soil surface, withdraw

a soil gas sample and determine the concentration of the

sample in the field or at the laboratory. Although used

successfully, unfortunately this technique can also

provide false negative results (i.e. zero concentrations) if

contamination is present and resides at a depth beneath

finer soil layers or high moisture bands (see e.g. Barber

et al. 1990b). Where shallow impacts are suspected in

more uniform aquifer/soil materials, soil gas surveying

may indeed provide a useful technique to determine

regions of impact – especially where NAPL is present in

the shallow subsurface. Of course, as depicted in Figure

3, the depth at which a soil gas sample is taken may be

critical to establishing if contamination is below. In the

case depicted in Figure 3, a gas sample would need

to be taken from below 1.25 m to detect hydrocarbon

vapours in the sample and to indicate contamination

is present. However, a shallower sample would yield a

non-detectable concentration and indicate the absence

of contamination if relied upon alone, yet residual NAPL

gasoline is actually present in the deeper soil profile near

the water table.

5.1.4 On-site and field analyticalmethods

Analysis of soil, soil gas, and groundwater samples in the

field is an essential element of a rapid site assessment.

To allow sound on-site decisions, field measurement

techniques for petroleum hydrocarbons and indicator

chemistry need to be not only qualitative but quantitatively

reliable. Such techniques have undergone ongoing

improvement over the last few decades. Techniques

include detector tubes, fibre optical chemical sensors,

colorimetric test kits, total organic vapour analytical

methods with FID and PID detectors, turbidimetric test

kits, immunoassay test kits, portable infrared detectors

and field gas detectors, and even more recently portable

GC/MS. On-line and real-time oxygen and volatile

hydrocarbon probes were developed by Patterson et al.

(2000), but these were largely developed for longer term

monitoring rather than rapid site assessment.

Field instrumentation and detectors may respond

differently to a volatile sample, depending on sensors type,

calibration stability, contact time and other environmental

parameters (e.g. humidity). Caution is required to ensure

false negative and positive results are not routinely

determined – especially where screening may lead to

misleading risk or remediation assessments. Additional

capabilities are shown in Table 3.

On-line and field analytical tools should not be solely

relied upon – laboratory confirmation is important. For

rapid site characterisation to be successful and adopted,

significant improvement in on-site sampling, measurement

and analytical capabilities is required.





Table 3. Table 1 from van Ree, D & Carlon, C 2003, ‘New technologies and future developments – How muchtruth is there in site characterisation and monitoring?’ Land Contamination and Reclamation 11(1), 37-48.Reproduced with permission

Table 1. Example of a comparison matrix showing the capability of available technologies to provide spatial and

analytical information

SPATIAL INFORMATION ANALYTICAL INFORMATION

Density Volume coverage1 Accuracy Sensitivity and selectivity

SAMPLING

Low flow groundwater

purging (vs. conventional

groundwater sampling)

(Puls and Barcelona 1996)

Flux chamber (vs. stand

pipe soil gas survey)

(Malherbe et al. 2002)

Pressure/vacuum

lysimeters (vs. leaching

tests on soil samples)

(Rouse et al. 2002)

ANALYSIS

Hand-held PID and FID

survey instruments

(US EPA 2000)

Gas chromatography (GC)

portable instruments

(US EPA 1998)

X-ray fluorescence

Energy-dispersive XRF for

metals in soil and sediments

(recently also metals in

water) (US EPA 2000)

PAH-UV spectrophotometry

(Steyer et al. 2002)

Rapid optical screening

tool

ROST-LIFs techniques

for heavy metals

(Barbafieri and Ciucci 2002)

–

Low sensitivity

with low volatility

compounds

Low sensitivity

with low solubility

compounds

Selectivity: no

differentiation among

individual constituents

Sensitivity: ppm range

Sensitivity: ppm range

(fast GCs)

Selectivity: high with

mass spectrometers

Selectivity: good

Sensitivity: low for

some elements

(e.g. Cr)

Low selectivity: no

individual compounds

Selectivity: good

Sensitivity: ppm

High

Collection from

vertical strata

No need for filteration

High

Natural soil-to-air

flux of volatile

compounds

High

Actual interstitial

void water is

collected

Quality control

is limited

Accuracy: soil

standards are

difficult to obtain

Accuracy:

agreement with

standard methods

Accuracy: good

agreement with

atomic absorption

Limited

Limited

In same cases

high heterogeneity

High

Collection from a

sphere around the

point of installation

Only surface soil

or conventional

sampling needed

Conventional

sampling and soil

handling is needed

In situ: point

and shoot mode

Intrusive: requires

conventional

sampling

Conventional

sampling and soil

handling is needed

Not jet mounted on

cone penetrometer

probes

Limited by costs

and time

Limited by costs

and time

Limited by costs

and set-up time

High

Quick and low cost

High

Quick and low cost

High

Quick, multi-

elements and

low cost

High

High

Quick, low cost and

multi-elementary

analysis



5.2 New and not-so-newapproaches

There is a wide range of possible techniques, tools and

strategies that could be used to characterise a petroleum-

impacted site – these include, for example, depth-

specific sampling, the use of isotopes, flux estimation

techniques, directional drilling, and reactive transport

modelling. Some ‘new’ and old approaches to site

investigation were reviewed some time ago (e.g. Davis

et al. 1992), as were standard operating protocols

(e.g. Barber 1996). They reported on the value of depth

profiles for defining groundwater contamination, the

need for purging of boreholes to achieve representative

sampling, the complications when sampling volatile

organics, and some new ideas in the use of passive

samplers (e.g. diffusion cells and dialysis cells). Some

of the lessons and techniques reported then remain

issues today or have not been adopted for use. Of

course, many organisations are currently taking steps

to improve procedures and guidance (e.g. Davis 2005;

NEPC 2006). We revisit some of these issues below,

and discuss others.

5.2.1. Depth-specific sampling

Multi-level sampling has been commonly employed

by researchers for some time (Davis et al. 1992, 1999;

Ronen et al. 1986) but less so in routine site

assessments. More recently, this has become more

SPATIAL INFORMATION ANALYTICAL INFORMATION

Density Volume coverage1 Accuracy Sensitivity and selectivity

Rapid optical screening

tool

ROST-LIFs techniques

for petroleum hydrocarbons

(Bujewski and Rutherford

1996)

Membrane interface probes

(MIP) for semi-volatile

organic carbon

Cone penetrometer

based – FID or PID

detectors (Fugro 2002)

Immunoassay kits (total

PAHs, PCBs, BTEX, etc.)

(US EPA 2000)

Geophysical methods in

general: e.g. electro-

magnetic and geoelectric,

magnetometry, GPR,

seismic reflection and

refraction methods, remote

sensing (van Deen 2002)

1 Investigated volume per unit measurement

Table 3. (cont.) Table 1 from van Ree, D & Carlon, C 2003, ‘New technologies and future developments – How much truth is there in site characterisation and monitoring?’ Land Contamination and Reclamation11(1), 37-48. Reproduced with permission

High

Low costs

High (up to 80

metres of probing

per day)

High

Low cost and time

High

Mounted on cone

penetrometer: real

time analysis, affords

nearly continuous

spatial data along

the profile

Near-continuous

spatial data along

the profile

Conventional

sampling and soil

handling is needed

High

Accuracy: good

agreement (80%)

and low (5%) false

negatives for detect/

non-detect data

Accuracy: semi-

quantitative

technique

Accuracy: semi-

quantitative analysis

In some cases

identification of

contaminant

hot spots

Selectivity: it does not

allow for the direct

quantification of


Selectivity: does not

allow for the direct

quantification of


Selectivity: they do

not differentiate

among individual

constituents

Sensitivity: good

No



acceptable for site investigations, although the analytical

costs can increase due to the increased number of

sampling locations. However, large uncertainties in

contaminant mobility, risk assessment and the target

dimensions for active remediation may remain where

depth-specific data is not obtained. Barber (1996) gave

a specific example of this for petroleum hydrocarbon

plume, where he compared data from multi-level depth

samplers and data from more conventional short-

screened boreholes. He found that data from the

conventional boreholes implied much greater dispersion

and much less plume movement than the multi-depth

samplers, indicating a lower risk profile than was actually

the case.

The reluctance to adopt depth profiling is understandable

if conventional approaches are taken. It may mean drilling

individual boreholes to separate depths, so adding

expense, and then every additional screened depth

means not only additional drilling costs but also

additional sampling and analytical expense. Where

appropriate three or four standard 40–50 mm diameter

short-screened piezometers could be installed in the one

drilled borehole, or where greater resolution is required,

narrow diameter tubing could be used with bundles of

access tubes and screens. This style of installation has

been used at numerous research locations and some

industry locations in Australia where the depth to the

water table is less than say 8 m (e.g. Davis et al. 1999);

for those cases syringes were used to purge and sample

each of the ports of the bundle tubes/screens. Figure 4

provides examples of such depth profiles, which were

sampled for hydrocarbons, inorganics and ‘well head’

parameters using plastic and glass syringes.

Figure 4. Depth profile of BTEX and naphthalene concentrations and EC measurementsin groundwater near the source of a plume (right panel) and 40 m down hydraulicgradient (left panel). The water table was about 0 m AHD. The depth profiles arelocated close to where groundwater is discharging to a marine environment, andshow increased EC at depth nearer the ocean, indicating the likely location of the‘saline wedge’ interface. The significant reduction in hydro-carbon concentrationsover the 40 m travel distance also indicates the potential for natural attenuation.

5.2.2. Purging boreholes

Recovering samples that are representative of aquifer

conditions is a prime goal of groundwater sampling.

Barber and Davis (1987a) and others stressed the need

for purging boreholes of 3–5 well volumes and/or allowing

well head parameters (e.g. DO, pH, EC, temperature, Eh)

to stabilise prior to taking a groundwater sample for

analysis. Micro-purging/pumping (also called low-flow

sampling or minimal drawdown sampling) has become

popular (see e.g. ASTM 2002; Puls & Barcelona 1996).

It was largely initiated by the need to reduce colloidal

movement into wells and thus avoid potential bias when

analysing groundwater samples for metal constituents.

Additionally, it allowed for greatly reduced volumes of

potentially contaminated water to be handled and

disposed to waste, and notionally reduced the potential

for changes in redox conditions in wells during purging.

The criteria set for minimal drawdown sampling is that

well head parameters stabilise prior to recovery of a

sample. If stabilisation is prolonged the protocol suggests

that 3–6 well volumes be extracted before sampling,

which is the established standard for conventional

groundwater sampling.

Increasingly, low-flow sampling has been adopted for a

wider range of chemicals in groundwater including organic

compounds, such as petroleum hydrocarbons. Low flow

sampling is not applicable if NAPL is resident in a well,

nor does it obviate the need to ensure samples are not

exposed to air or polymer materials. For example, low

flow purging and sampling is sometimes carried out using

a peristaltic pump, but this is only valid if the groundwater

sample is taken prior to contact with any of the flexible

tubing used in the pump, to avoid sorption onto the tubing

from the pumped groundwater stream.

5.2.3 Sampling for organic compounds

The hazards of sampling and handling samples

containing volatile and other organic compounds typical

of those found in petroleum hydrocarbon oils and fuels

have long been known (Barcelona et al. 1984, 1985;

Holm et al. 1998; Reynolds et al. 1990). Methods were

developed to overcome some of these sampling and

analytical difficulties (e.g. Davis et al. 1992; Pankow et al.

1984; Patterson et al. 1993).

In short, samples should be recovered to avoid contact

with the atmosphere to minimise volatile loss from and

oxygen ingress to the sample, and in addition samples

should be stored to minimise contact with plastic or

polymer materials to minimise sorption losses from the

sample. In some studies, all materials other than

borosilicate glass were observed to remove volatile

compounds from a water sample. Because of these

potential handling and storage issues, and because

organic compounds can biodegrade, samples should

be analysed as soon as possible after recovery, and

certainly well within the standard holding times for

samples prior to analysis.

5.2.4 NAPL characterisation

Although present in part, surprisingly few of the guidance

documents target the NAPL phase for measurement,

quantification or analysis separate from the soil,

groundwater or air phases. Certainly, the importance

of LNAPL is alluded to in many documents and

measurement in soils is common, but few provide detail

on LNAPL thickness monitoring, on whole oil analysis

for fingerprinting and confirmation of oil/fuel type, on

baildown or other well NAPL tests that would provide an

indication of NAPL mobility in the aquifer, the API (1996)

guide being an exception.

Huntley (2000) and others (e.g. Johnston et al. 2002)

provide theoretical and practical application of the use of

baildown tests on the NAPL phase in wells to determine

NAPL transmissivity. Such information assists in the

assessment of the mobility of the NAPL and its ultimate

recoverability if remediation is required.

Compositional changes in NAPL also can lead to

changed risk profiles due to altered partitioning to soil

gas (vapour) and dissolved groundwater phases, and

due to new compounds being formed during weathering

and biodegradation. The API (1996) guide notes this

possibility. Whole oil analysis also allows fingerprinting

of NAPL product to assist with identification of product

type and possible ownership.

5.2.5 Flux estimation

Many of the guidance documents seek to characterise

sites with respect to soil or water concentration threshold

values. This is to be expected given that regulation is

primarily based on concentration thresholds. However,

contaminant mass discharge (mass/time) across a control

plane is also a measure of potential receptor loading.

There are increasing efforts to determine and measure

flux/discharge/mass loading rates – both (i) downgradient

of suspected source zones, which gives source

discharge/fluxes, and (ii) contaminant discharge across

a compliance control plane as an estimate of receptor

exposure or off-site discharge. Point and integral flux

estimation techniques have been developed.





Point flux estimates

Contaminant mass discharge can be estimated from

contaminant fluxes measured by the passive flux meter

(PFM), an innovative technology developed at the

University of Florida (e.g. Annable et al. 2005; Hatfield

et al. 2004). This is a point scale measurement involving

the deployment of socks of tracer-laden sorbent into the

screened section of pre-drilled boreholes for some period

of time, after which the socks are removed. The mass

removed over the time period is measured along with

the mass of sorbed contaminant. From this, the flux

of groundwater past the sock/borehole and flux of

contaminant to the borehole is determined. If deployed

across the cross-section of a plume or source zone, for

example, the PFM technique provides a total mass flux

estimate of water and contaminant moving in groundwater

beyond that point. A disadvantage of this technique is

the point-scale nature of the measurement. Analytical

costs may also be a disadvantage if fine scale measures

are taken or multiple deployments are required, say

before and after a treatment strategy.

Integral flux estimation

Other techniques are also used to establish net

groundwater contaminant flux. Teutsch et al. (2000),

Ptak et al. (2003), Bayer-Raich et al. (2004) and others

from that group developed an integral pumping test.

The test involves pumping groundwater from a bore or

series of boreholes across the groundwater flow direction

downgradient of a source at a contaminated site, and

recovering a time series of samples from the pumped

effluent of the boreholes. During pumping, as the capture

zones of the pumping bores increase, the concentration

of groundwater contaminants is measured as a function

of time at each of the pumping wells. Based on the

time series of groundwater quality data and modelling

inversion, the flux of contamination moving in groundwater

is determined. An advantage of this technique is that it

integrates data over a much larger volume of the aquifer,

rather than providing point source estimates. A

disadvantage of this technique is the large volumes of

contaminated effluent water that would need to be

collected and disposed of.

5.2.6 Capillary fringe

LNAPLs, being less dense than water, pool on the water

table or reside within the zone of water table fluctuation.

As indicated earlier, hydrocarbon components partition

to the soil gas and groundwater phases. Few

characterisation techniques have a consistent strategy

for sampling/monitoring with depth continuously across

the capillary fringe, apart from recovery of gas samples

above this zone and water samples below this zone,

or perhaps recovery of soil material across this zone.

Suction lysimeters have been used in the vadose zone

to recover soil moisture for analysis. Commonly this is

carried out for inorganic chemical species of interest

rather than volatile compounds (see e.g. Capuano and

Johnson 1996).

Diffusion cells were developed specifically to determine

volatile hydrocarbon concentrations (e.g. benzene) and

gases (e.g. methane, oxygen) across the capillary fringe

and in water saturated or vadose zone conditions. Initially

these were developed by Barber and Briegel (1987).

Diffusion cells consist of coiled teflon tubing installed

in backfilled boreholes with nylon access lines to the

ground surface. Cells can be purged with inert gas which

equilibrates with groundwater when passing through the

cell. Examples are given of the use of diffusion cells by

Barber and Davis (1987b), Barber et al. (1990a), Davis et

al. (1992) and more recently they have been automated

for oxygen and volatile organic compounds (Davis et al.

1995; Patterson et al. 2000).

5.2.7 Combined technologies

There is an increasing trend toward combining

technologies to accelerate programs of investigation.

This is most evident in the programs and activities

espousing accelerated site characterisation or the Triad

approaches. Further development in this area adds

value and potentially reduces costs. For example, cone

penetrometers that allow downhole geophysics, and

on-line sampling/analysis at multiple elevations in the one

hole give stratigraphy and water/soil/vadose zone quality

data in one pass. Such combined technology has been

routinely available overseas, but less so in Australia.

Another example is the combination of field analytics and

sensors, with web sites for data collation and presentation

to facilitate real-time characterisation. This, combined

further with models of site conditions, would provide a

powerful tool for site application. Few, if any, of these

combined systems appear available in Australia. Whilst

research is underway internationally, further development

in Australia seems needed.

5.2.8 Directional and alternate drilling

Infrastructure on sites impedes access to the subsurface

– directional drilling is becoming more commonly available


and can be used to provide greater coverage where

infrastructure and hardpan are evident on a site. This

rarely seems to be used in Australia and there appears

to be no suggestion for its use in the guidance available.

A challenge may be to provide similar multipurpose

capability in directional drilling equipment that is currently

available for ‘push-rod’ type rigs.

Additionally, increasingly sonic or vibration rigs are being

made available. These provide the opportunity, depending

on the technique available, to recover more intact and

detailed core, to drill more quickly to depth, and to

produce less spoil or waste. This is especially the case

for unconsolidated materials, but vibration rigs are also

becoming available for consolidated aquifer and

soil materials.

5.2.9 Coupled reactive transportmodelling

Increasingly, coupled reactive transport models are being

developed and utilised. Holistic incorporation of transport

processes, dispersion processes, and the relevant

biodegradation pathways is rarely available. PHT3D (see

Prommer et al. 2002, 2003) is a recently developed code

that embodies these processes. These models allow

consideration of fringing processes along plume boundaries

where electron acceptors are only available external to

a hydrocarbon plume, but also allow consideration of

plume-core reactive processes where oxidised mineral

phases are present (e.g. iron oxides, manganese oxides)

and methanogenesis may be active. These considerations

are increasingly required in modern assessments of

plume behaviour and such tools need to be made user-

friendly and efficient so as to be routinely available for

application where rapid assimilation and integration of

data is needed in site assessments.

5.2.10 In situ or passive techniques

In situ (passive) monitoring or measurement devices

(Barber & Briegel 1987; Ronen et al. 1986) can provide

greater representativeness of in-ground conditions – for

example to overcome pumping and purging difficulties in

the field, sorption/desorption issues with hydrocarbons

and polymer materials, and losses of volatile compounds

during sampling. In situ monitoring devices have numerous

advantages: sampling can be rapid and efficient, and

since no pumping is required little disturbance of

groundwater occurs during monitoring. In situ sampling

can also provide the opportunity to obtain detailed

information on the vertical stratification of groundwater

quality. Some additional examples of in situ techniques

are given below to illustrate these advantages. The

diffusion cell was presented earlier as a technique that

could be used to target the capillary fringe.

Dialysis cells consist of small vials of distilled water

capped with a permeable membrane which allows ion

transfer from groundwater into an aqueous phase within

the vial until chemical equilibrium is achieved. Ronen et

al. (1986) used a string of dialysis cells within a cased

borehole to obtain vertical profiles of inorganics and

dissolved oxygen in groundwater. Davis et al. (1992)

reported on the results of field trials comparing the

performance of dialysis cells with bundled short-

screened piezometers in monitoring nutrient accessions

to groundwater under urban parkland areas. The dialysis

cells provided groundwater quality data which had the

same overall depth and time trends as the more

conventional and more time-consuming multi-level

sampling using piezometer bundles. Dialysis cells might

be more appropriate for inorganic parameters rather than

hydrocarbons and organic compounds, but could be

used to determine electron acceptor/donor parameters

during natural attenuation assessments.

Karp (1993) developed a diffusive sampler to provide a

passive in situ method for long-term monitoring of volatile

organic compounds (VOCs) in groundwater. The sampler

was constructed of a sorbent tube that fits inside a

specially designed sampling chamber equipped with a

diffusional membrane that is not permeable to water but

has a high permeability rate for organic vapours. VOCs

in the groundwater, having relatively high Henry's Law

constants, enter the chamber by molecular diffusion

and are collected by the sorbent. After a predetermined

exposure period, the sorbent is retrieved for

laboratory analyses.

As mentioned earlier, diffusion cells developed by Barber

and Briegel (1987) have been automated for on-line

monitoring of oxygen and volatile organic compounds in

subsurface environments (Davis et al. 1995, Patterson et

al. 1995, Patterson, Davis & Johnston 1999, Patterson,

Davis & McKinley 2000). The VOC probes measure total

concentrations of volatile organic compounds and avoid

sampling and analysis issues and costs. They have been

applied to sites for monitoring VOC fate and also where

monitoring of active remediation is required, e.g. during

air sparging.



6.1 Guidance documentsOverall the guidance documents provide structure and

direction for improved site characterisation. At one level,

these provide a mechanistic set of ‘rules’ to follow to

achieve an end – and this is needed where expertise is

lacking and the end point is clear. Others are structured

as optional strategies to achieve the best outcome –

perhaps where the intent of the investigative effort is clear

and the skill/expertise base is good. At another level the

documentation becomes over prescriptive or tome-like,

making its use inefficient or difficult to assimilate – perhaps

assuming the end point or intent of the investigation is

unclear and where step-wise instruction is warranted.

Examples of each of these are evident in the guidance

documents reviewed.

Several aspects seem essential – that the investigation

at minimum meets PAR – i.e. is purposeful, adequate

and representative.

6.1.1 Purposeful

A site investigation needs to be purposeful – that is,

purpose-driven. Data quality objectives (DQOs) appear

in some guidelines (see e.g. AS 2005; US EPA 2006),

and were developed to be a trigger for serious thought

around the purpose of investigations and hence each

of the planned individual tasks that make up a site

characterisation effort. It is argued by some (e.g. Crumbling

2002) that the emphasis has been too much on ‘data

quality’ and not enough on the ‘objectives’ when utilising

the DQO approach.

A challenge is defining the purpose (or objectives). For a

site investigation to be precisely planned all stakeholders

may need to be active in defining the purpose. Recognising,

for other than simple sites, that removal of all mass from

a contaminated site may not be practicable, the setting

of the purpose becomes a critical aspect of the

characterisation. Is the purpose:

• to keep total hydrocarbon exposures from all phases

below a threshold, and if so, how is this to be

allocated amongst the phases?

• to avoid off-site discharge of a plume of hydrocarbons?

• to establish the stability of a plume?

• to establish no vapour exposure?

• to ensure NAPL thicknesses in all wells remain below

a sheen?

Or perhaps it is a combination of some of these, and

others. Agreeing this with stakeholders becomes a fruitful

first step, albeit somewhat resource- and time-intensive

to achieve.

The argument is a little cyclic, in that to establish a

stakeholder-agreed purpose requires a sound conceptual

site model (CSM), if not a predictive model for the site,

and to have a negotiated position on threshold values.

This is not always possible – but such an approach

would require discussion between regulators, site

owners and consultants, bringing benefit to a site

characterisation strategy.

6.1.2 Adequate

A site investigation needs to be adequate – that is,

adequate in extent and quality to meet the purpose

of the investigation. For adequate coverage, how many

samples are required at what locations and in which

phases? This needs to be much more driven by the

purpose (Section 6.1.1). Crumbling et al. (2001) argue

that using field analytical technologies in the context

of a dynamic work plan, and careful management of

sampling, analytical and decision uncertainties, can

significantly bring down the costs of contaminated site

investigations and clean-ups, while improving confidence

in project decisions.

Whilst many of the documents refer to the need to

provide sufficient supporting data to determine the

contamination status of a site with an acceptable level

of confidence (see e.g. AS 4482.1-2005), rarely is the

level of acceptability or level of confidence defined. The

challenge is to find an acceptable level of confidence

agreeable between site owners and regulators, to meet

end point objectives of the characterisation to provide

‘adequate’ data. This needs to be balanced against

the uncertainties in risk assessments, and the cost-

effectiveness of remediation strategies, given a set or

limited quantum of data.

6. Synthesis and conclusions

6.1.3 Representative

A site investigation needs to be representative – that is,

sampling and investigation strategies and techniques

must provide data that are representative of the

subsurface environment and site conditions. Crumbling

(2002) asserts that data representativeness is fundamental

to data quality. The data quality model for contaminant

data can sometimes remain focused on analytical data

quality methods to the neglect of strategies to

accommodate sampling from a heterogeneous

environment. Crumbling (2002) argues that for the same

overall cost, a greater spread of samples across a site

with (even greater) reduced analytical certainty from

laboratory or field screening will have a lower uncertainty,

and therefore be more representative than fewer samples

analysed to a high degree of accuracy. Development of

the ASC- and Triad-based technologies (e.g. rapid soil

and groundwater sampling tools, field-portable analytical

instrumentation, decision-support software) has moved

site characterisation in this direction – with a greater

potential to provide cost-effective, high density, adaptive

sampling needed to assure data representativeness.

Combined with dynamic management and decision

making, this offers to support a next generation data quality

model that explicitly manages sampling uncertainties,

allowing greater representativeness.

6.2 Final observations1. A risk-based approach should be taken as the

starting point for site characterisation, since this

forces consideration of the regulatory regime and

exposure pathways, and focuses effort on

establishing a robust conceptual model – with field

investigations that target the improvement and

modification of this model.

2. A clear information objective is important, embodying

data quality objectives and achieving representative

sampling of a site.

3. Important to any site characterisation is the

derivation of a site conceptual model that integrates

what is already known about a site, and identifies

both what still needs to be discovered, and how that

information should be used.

4. Choices of site investigation approaches should

be made on the basis of improvement of the site

conceptual model. The site conceptual model also

serves as the basis for risk assessment and

remediation. The information needed for risk

assessment and remediation planning is not

necessarily the same.

5. Site characterisation plans need to be flexible and

adaptable to allow feedback on possibly real-time

results. This kind of dynamic approach to site

characterisation needs to be considered as a part

of overall site investigation strategy, before site

characterisation mobilisation. It also impinges on

the reliance on conventional sample-to-laboratory

systems, as laboratory data can take longer to be

generated. Dynamic approaches may also need

to encompass remediation planning.

6. If representivity is to be emphasised, perhaps the

analytical precision of conventional laboratory (off-

site) analyses could be traded off against greater

data intensity on-site, especially when comparing

sources of error from sampling, and sources of

uncertainty from site heterogeneity and variability.

7. For groundwater investigations, guidance

documents generally promote a minimum of three

or four boreholes. In practice, on average a greater

number of sampling boreholes is used. Greater

use could be made of statistical sampling theory,

statistical tests of significance, and geostatistical

analysis to handle aquifer and geochemical

heterogeneity.

8. Site investigation data needs to be assessed over

time, as well as in space, so that trends in

contaminant behaviour can be assessed. The depth

dimension is often neglected in air, water and soil

phases. Whilst depth sampling of soils/sediments

(whether in the vadose zone or groundwater) is

mentioned in several guidance documents, it has

not been formalised. Depth-discrete sampling of

groundwater is mostly ignored.

9. A variety of site characterisation techniques are

available for on-site analyses, from on-site sensors

to geophysical techniques. Validation and

improvement is required to avoid false negative

and positive outcomes, and to build reliability and

confidence into rapid assessment practices.





10. Development of new tools for on-site use in site

characterisation is increasing, but if ASC or Triad is

to be pursued, further development of new or novel

sensor and site characterisation techniques should

be pursued – especially those that would allow

rapid on-site decision making and achieve reliable

outcomes at reduced cost. Combining ‘continuously

available’ data with models on-line could also be

pursued. This is near readily available for groundwater

flow, however, where geochemistry and reactive

transport is important on-line real-time linkages

between data collection and models is problematic

due to the computational intensity of such codes.

11. The use of ‘direct push’ tools as opposed to

conventional drilling, and a variety of attachments

and sensors which can be used with these direct

push tools to collect site investigation information,

is desirable. This allows more real-time information

gathering and implementation of dynamic site

characterisation strategies. Innovation in this area

should be encouraged.

12. In Australia, implementation of Triad would require

upskilling of all elements of site characterisation

(planning, on-site interpretation including sophisticated

modelling, and technology availability and

deployment) in consulting agencies and/or industry,

and integration of these skills with the regulatory

approvals process – possibly on-site.

13. Harmonisation of the regulation of site characterisation

through NEPM or other mechanisms may assist the

practice of site characterisation, but reduced flexibility

needs to be avoided to allow for continued innovation.

14. Greater guidance on the use and application of

numerical models to integrate site characterisation

data could be useful. The Murray-Darling Basin

Commission issued guidelines for water resource

groundwater flow modelling in 2000. Prommer et al.

(2003) provided an initial basis for petroleum plumes

in groundwater. There are no Australian guidelines

for modelling multiphase hydrocarbon behaviour.

15. There is a need to continue to facilitate knowledge

transfer across regulators, contaminated site owners,

service providers and the academic community.

16. The scalability of site investigation plans and

technologies should be assessed – from UST and

service station scale, to depot and terminal scale

and perhaps refinery or multiple source complex

mega-site scale.

17. US documentation (ASTM, API, etc.) includes

management as part of guidance in many instances,

whilst the NEPM does not. Interestingly, the NSW EPA

Service Station Guidelines did include remediation

options as part of the guidance. A perceived difficulty

in embedding management options in such guidance

is the lack of stability in the range of technologies

on offer.

18. Research and innovation is needed to quantify and

optimise the value of gathering additional data so

as to minimise uncertainty during assessment – to

provide more precise definition of risks and costs

for clean-up applications. For example, whilst the

multiphase behaviour of petroleum hydrocarbons is

recognised, the value of extra data in any one phase

in reducing uncertainties in risk assessment or the

selection of remedial options is not well defined.

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ANZECC/ARMCANZ 2000, Australian and New Zealand

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ANZECC/NHMRC 1992, Guidelines for the Assessment

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Extract of the document Review of the National

Environment Protection (Assessment of Site Contamination)

Measure: Summary of Submissions received in relation

to the Issues Paper for the Review of the Assessment

of Site Contamination NEPM available from the National

Environmental Protection Council (NEPC) and copyright

NEPC Service Corporation (used with permission).

2.3.1 Total Petroleum Hydrocarbons(TPH) – Schedule B(1)

Issue 15

Is there a need for nationally adopted investigationlevels for TPH in soils and waters, and by whatprocess should they be developed?

Submissions

In commenting on this issue, the majority of submissions

(including 3, 4, 6, 7, 8, 9, 11, 13, 14, 16, 19, 20 and 23)

supported the adoption of nationally-endorsed

Investigation Levels for Total Petroleum Hydrocarbons.

Submissions 7 and 12 highlighted that there are already

Investigation Levels for non-volatile fractions, but not for

volatile fractions. Submissions 1 and 12 highlighted the

existence of Guideline Values adopted in NSW, although

submission 1 commented on the apparent inconsistency

between these, guidelines used in Qld and the NEPM.

No submission argued that these Investigation Levels

weren’t required.

Several submissions advocated the adoption as

Investigation Levels of criteria already developed.

These include:

• those from the TPH Submissions 3, 6, 16

Working Group

• unspecified ‘overseas Submission 14

health (only) values’

• those under development Submission 14

by ISO TC/190

• Indoor Vapour Submission 23

Intrusion Model

Other submissions commented on the approach to be

used in developing Investigation Levels without specifying

any existing set of guideline values. These included:

• sensitive species distribution Submission 4

approach

• consideration of relevant Submission 9

international research

and risk-based standards…

suitably adapted to Australian

conditions

• screening level guidelines Submission 12

based on low cost total

analysis methods with

fractionation between aliphatic

and aromatic

• derivation based on aliphatic Submission 12

and aromatic fractionation

• appropriate research Submission 13

to fill knowledge gaps and

stakeholder consultation

• consideration of factors other Submission 16

than health (including volatility,

flammability and aesthetics.

A tiered approach.

In keeping with the comments about fractionation of TPH,

Submission 13 stated that a more careful definition of

TPH is required (see Issues Paper discussion of Issue 18).

Response

TPH is a very complex issue and the NEPM review will

need to consider the practicality of developing a validated

model or adopting an existing set of investigation levels.

Given the level of response to this issue, the review will

consider this a priority issue.

APPENDIX A. Summary responses to the NEPM IssuesPaper (used with permission)

Issue 16

Are there guideline levels currently being used for theassessment of TPH in soils and waters which couldusefully be adopted in the NEPM as interim levels, inorder to give national consistency in site assessment?

Submissions

Several submission suggested guideline levels, already

developed, which could be used, as detailed below.

• those from the TPH Submissions 3, 6, 16

Working Group

• US EPA or the Dutch Submissions 4, 13

Guidelines

• Queensland EPA Submission 11

• Industry-derived TPH Submissions 9,12, 13

guidelines, AIP, Australian

Oil Industry Guidelines

• NSW EPA Submission 23

• Western Australian Submission 13

• Turzcynowicz, Fifth National Submission 14

Workshop on the Assessment

of Site Contamination

Response

This information will be useful during the possible

development of a national approach on this issue.

Issue 17

What are the issues involved with the adoption of aninterim set of HILs/EILs for TPH/aliphatic and aromatichydrocarbons? For example:

• are the impacts of these compounds sufficientlywell understood to justify such an approach?

• which set(s) of levels would be chosen forconsideration?

Submissions

Notwithstanding the submissions on Issue 16, two

submissions (1, 9) argued against the adoption of an

interim set of guidelines, preferring to see long-term

solutions developed straight away.

Some submissions (3, 6, 16) contended that the impacts

of TPH/aliphatic and aromatic hydrocarbons are well

understood to justify an interim set of HILs/EILS. One

submission (7) stated there are sufficient toxicology and

indoor measurement data to indicate that TPHs present

a serious issue to human health.

A number of submissions identified fractionation of

aliphatic and aromatic hydrocarbons as an important

issue, and that there was a need to extend the range

of MAHs for which Investigation Levels are available to

include those beyond the BTEX group (7, 12, 13, 19).

One submission (15) recognised that various components

of TPH have different environmental health impacts, and

this needs to be accounted for. One submission (1) argues

for Investigation Levels relevant to the components of

common mixtures such as kerosene, diesel and aviation

fuels. One submission (12) refers to the inclusion

of toxicologically relevant compounds in lists of

Investigation Levels.

One submission (7) highlights that the toxic effects of

these compounds seem well understood, but that only

one exposure scenario has been properly modelled in

the Australian context.

Recommendations on the adoption of specific criteria

reflected the comments made in response to Issue 16,

as discussed above.

Response

This information will be considered during the possible

development of a national approach on this issue.

Issue 18

What are the possible benefits of differentiating TPH fractions, based on aliphatic and aromatichydrocarbons, and developing new measurementmethodologies? By what mechanism(s) could suchmethodologies be developed?

Submissions

Four of the submissions mentioned the greater toxicity of

aromatic hydrocarbons compared to aliphatic (7, 13, 14,

23), and there was a recognition that differentiating TPH

fractions would allow for a better understanding of the

risks posed by petroleum components as contaminants

(3, 6, 9, 13, 16). In addition, one submission (23) stated

that differentiation would allow appropriate threshold

criteria to be applied and one submission (19) suggested

that it may assist in understanding bioavailability.

Four submissions (3, 6, 9, 16) suggested that CRC

CARE was the appropriate avenue for developing the

necessary methodologies.

One submission (7) pointed out that international working

groups have provided guidance on analytical differentiation

methodologies which was put forward during TPH HIL


APPENDIX A. Summary responses to the NEPM Issues Paper



development work in 1998. One submission (6) referred

to a method for differentiating between TPH fractions

based on solvent exchange. This had been put forward

by the TPH Working Group.

Response

This issue will need to be considered carefully as it may

have a significant economic impact on site assessments.

2.3.2 Fuel components – Schedule B(1)

Issue 19

Under what circumstances should fuel additives and their degradation products be assessed at fuelstorage sites? Should a small number of indicatoradditives be identified which can be used as initialscreening substances for the presence of additivesin the subsurface?

Submissions

Seven submissions (1, 3, 6, 13, 16, 19, 23) raised that

fuel additives and their degradation products should be

assessed where the site history reveals or suspects they

have been used, stored or disposed of at the site being

investigated: for example, at sites where imported fuel is

being used (3, 6, 16). One submission (23) felt that a

specific GCMS scan should be the preferred approach

as it is likely to pick up contaminants of concern. Two

submissions (7, 14) raised the issue that there is a lack of

data on the subject to answer the question and suggested

further research and a needs analysis be conducted.

Three submissions (3, 6, 16) raised that a risk assessment

should be done on different additives to assess whether

there is potential human health or ecological risk at the

levels at which they are added in fuel.

Response

This information will be considered during the possible

development of a national approach on this issue. Given

this issue is linked with fuel products, it is appropriate

that it be considered with petroleum hydrocarbon issues.

Issue 20

Should investigation levels for fuel additives bedeveloped for soils and groundwaters/surface waters?

Submissions

Most submissions (3, 16, 16, 7, 11, 13, 14, 23, 1) gave

qualified support to the development of ILs for fuel

additives based on a needs analysis and risk assessment.

One submission (23) clarified that investigation levels

should be developed for fuel additives if they are ‘risk

drivers’.

Response

Further development should be considered when

addressing the comments raised at issue six. Given this

issue is linked with fuel products, it is appropriate that it

be considered with petroleum hydrocarbon issues.

2.3.5 Assessment of Impacts fromVolatile Substances – ScheduleB(7a) & B(7b)

Issue 25

Should the NEPM provide more information andguidance on assessment of the impacts and risks fromvolatile substances, given the rapid developments inthis field of science? If so, what further informationand guidance should be provided in the NEPM?

Submissions

Most submissions (1, 3, 6, 7, 9, 11, 12, 13, 14, 16, 20,

22, 23) called for more guidance and models on the

assessment of impacts and risks from volatiles. There

were additional comments (14, 9) also made on the

analytical approaches and field methods to be employed

in risk assessment.

Two submissions (7, 23) raised the need for a validated

model on the movement of volatiles into buildings in

Australian conditions.

Response

These views are supported. The review process will

examine the options. Final guidance on these issues will

depend on the availability of validated models and the

practicability of their application.

2.4 SITE ASSESSMENT

2.4.1 Data Quality Objectives and PoorQuality Site Investigations, includingLack of Vertical Delineation andcharacterisation of Contamination –Schedule B(2)

Issue 28

Is more guidance required on the application of DQO processes?

Submissions

Eight submissions (1, 3, 9, 10, 11, 16, 18, 23) raised that

more guidance was needed on the application of DQO

processes. Two submissions (14, 22) commented that

further guidance was not needed. Two submissions (12,

14) raised that the NEPM approach to DQO should be

linked with the AS4482.1. One submission (23) raised

that NEPC may consider adopting the DQO section of

the Draft Guidelines for the NSW Site Auditor Scheme

into the NEPM.

Response

There is a general consensus that improvements to

DQO processes would be appropriate. This issue will

be considered for development during the review.

Issue 29

What further guidance should the NEPM provide on the collection of field parameters? For example,would it be useful if the guidance is provided in theform of checklists?

Submissions

Four submissions (3, 6, 10, 16) raised that further

guidance on the collection of field parameters should be

provided. The majority of submissions (1, 3, 6, 7, 8, 9,

10, 11, 20, 23) agreed that checklists would be useful

and some cited Australian Standards and US EPA

publications as examples. Four submissions (11, 12, 18,

19) raised that the NEPM should concentrate on guidance

on principles rather than prescribing specific tools such

as checklists.

Response

The review will consider giving relevant guidance on

this issue.

Issue 30

What guidance should be provided so that verticaland lateral delineation and characterisation ofcontamination can be satisfactorily achieved?

Submissions

Three submissions (3, 6, 16) raised that vertical and

lateral delineation of contamination should be conducted

to establish a ‘criteria’ boundary. A number of submissions

(12, 19, 1, 20) suggested that reference to existing

guidelines should be included. Other submissions (13….)

supported the need for guidance. One submission (14)

sought guidance on the maximum general depth at

which most contaminants will not pose a health risk for

typical land uses.

Three submissions (1, 12, 19) raised the DQO process

as a means to achieve improved outcomes on this issue.

Response

The review will consider giving relevant guidance on

this issue.

2.4.2 Groundwater assessment –Schedule B(2) & B(6)

Issue 31

Should further guidance be provided on the technicalaspects of groundwater assessment, and if so, whatshould be the scope and content of this guideline?

Submissions

Ten submissions (3, 16, 7, 6, 9, 11, 23, 12, 19, 13)

supported the provision of further guidance on the

technical aspects of groundwater assessment. One

submission (14) recommended further interaction with

Standards Australia. Seven submissions (3, 6, 16, 12, 1,

19, 18) suggested that this be done by reference to or

incorporation of existing guidance.

Response

Some of the submissions contained detailed information

about the desirable requirements. These comments will

be useful in reviewing the current guidelines.



2.4.3 Assessment of fuel storage sites –Schedule B(2)

Issue 32

Is it appropriate to develop additional guidance forsites with fuel storage uses, given that genericguidance already exists under the NEPM such assampling design, data collection, and assessment of groundwater contamination?

Submissions

Six submissions (3, 6, 11, 16, 14, 13) supported the

need for additional guidance for sites with fuel storage.

Six submissions (9, 12, 1, 18, 19, 23) did not support

the need for additional guidance. One submission (7)

suggested that evaluation and assessment of the

limitations of current techniques should be undertaken

prior to deciding on providing further guidance.

One submission (12) suggested jurisdictions could

develop their own guidance if they did not consider the

current guidance adequate.

Response

There are differing views on the provision of specific

guidance. This issue will be considered in the prioritisation

of the overall review.

Issue 33

Should a guideline specify protocols for theassessment of sites involving fuel storage? For example:

• what standard sampling approaches should beused that will enable proper assessment of currentand former tank areas, in ground pipework andbowser areas?

• what should be the linear separation of samples in open pits and at what depths below surfaceshould they be taken?

• how should soil stockpiles be sampled andmanaged to prevent environmental harm?

Submissions

Five submissions (3, 6, 13, 16, 17) supported specific

protocols, whereas one submission (19) did not support

a descriptive approach.

Sampling

Three submissions (3, 6, 16) supported a prescriptive

standard sampling approach. One (22) suggested

adopting national best practice. One (23) suggested that

good record keeping on the part of site occupiers would

enhance the development of appropriate sampling

strategies based on the information.

Linear separation

One submission (23) referred to the NSW service station

guidelines. Four (3, 6, 16, 22) suggested that this was

too site-specific to be able to prescribe guidelines.

Stockpiles

Two submissions (3, 6) provided a formula for sampling

per unit volume with composites. One (7) emphasised

the importance of relevant stakeholders in making a

determination. One (12) did not think that it was a high

priority. Three submissions (13, 22, 23) supported

additional guidance for sampling of stockpiles.

Response

There is a number of complex technical issues raised in

the submissions and will be considered in greater detail

during the review.



Petroleum Vapour Model Comparison: Interim Report for CRC CARE

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Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons

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